Store the IOMMU mapping created by the device core of each Exynos DRM
sub-device and restore it when the Exynos DRM driver is unbound. This
fixes IOMMU initialization failure for the second time when a deferred
probe is triggered from the bind() callback of master's compound DRM
driver. This also fixes the following issue found using kmemleak
detector:

unreferenced object 0xc2137640 (size 64):
  comm "swapper/0", pid 1, jiffies 4294937900 (age 3127.400s)
  hex dump (first 32 bytes):
    50 a3 14 c2 80 a2 14 c2 01 00 00 00 20 00 00 00  P........... ...
    00 10 00 00 00 80 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<3acd268d>] arch_setup_dma_ops+0x4c/0x104
    [<9f7d2cce>] of_dma_configure+0x19c/0x3a4
    [<ba07704b>] really_probe+0xb0/0x47c
    [<4f510e4f>] driver_probe_device+0x78/0x1c4
    [<7481a0cf>] device_driver_attach+0x58/0x60
    [<0ff8f5c1>] __driver_attach+0xb8/0x158
    [<86006144>] bus_for_each_dev+0x74/0xb4
    [<10159dca>] bus_add_driver+0x1c0/0x200
    [<8a265265>] driver_register+0x74/0x108
    [<e0f3451a>] exynos_drm_init+0xb0/0x134
    [<db3fc7ba>] do_one_initcall+0x90/0x458
    [<6da35917>] kernel_init_freeable+0x188/0x200
    [<db3f74d4>] kernel_init+0x8/0x110
    [<1f3cddf9>] ret_from_fork+0x14/0x20
    [<8cd12507>] 0x0
unreferenced object 0xc214a280 (size 128):
  comm "swapper/0", pid 1, jiffies 4294937900 (age 3127.400s)
  hex dump (first 32 bytes):
    00 a0 ec ed 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<3acd268d>] arch_setup_dma_ops+0x4c/0x104
    [<9f7d2cce>] of_dma_configure+0x19c/0x3a4
    [<ba07704b>] really_probe+0xb0/0x47c
    [<4f510e4f>] driver_probe_device+0x78/0x1c4
    [<7481a0cf>] device_driver_attach+0x58/0x60
    [<0ff8f5c1>] __driver_attach+0xb8/0x158
    [<86006144>] bus_for_each_dev+0x74/0xb4
    [<10159dca>] bus_add_driver+0x1c0/0x200
    [<8a265265>] driver_register+0x74/0x108
    [<e0f3451a>] exynos_drm_init+0xb0/0x134
    [<db3fc7ba>] do_one_initcall+0x90/0x458
    [<6da35917>] kernel_init_freeable+0x188/0x200
    [<db3f74d4>] kernel_init+0x8/0x110
    [<1f3cddf9>] ret_from_fork+0x14/0x20
    [<8cd12507>] 0x0
unreferenced object 0xedeca000 (size 4096):
  comm "swapper/0", pid 1, jiffies 4294937900 (age 3127.400s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<3acd268d>] arch_setup_dma_ops+0x4c/0x104
    [<9f7d2cce>] of_dma_configure+0x19c/0x3a4
    [<ba07704b>] really_probe+0xb0/0x47c
    [<4f510e4f>] driver_probe_device+0x78/0x1c4
    [<7481a0cf>] device_driver_attach+0x58/0x60
    [<0ff8f5c1>] __driver_attach+0xb8/0x158
    [<86006144>] bus_for_each_dev+0x74/0xb4
    [<10159dca>] bus_add_driver+0x1c0/0x200
    [<8a265265>] driver_register+0x74/0x108
    [<e0f3451a>] exynos_drm_init+0xb0/0x134
    [<db3fc7ba>] do_one_initcall+0x90/0x458
    [<6da35917>] kernel_init_freeable+0x188/0x200
    [<db3f74d4>] kernel_init+0x8/0x110
    [<1f3cddf9>] ret_from_fork+0x14/0x20
    [<8cd12507>] 0x0
unreferenced object 0xc214a300 (size 128):
  comm "swapper/0", pid 1, jiffies 4294937900 (age 3127.400s)
  hex dump (first 32 bytes):
    00 a3 14 c2 00 a3 14 c2 00 40 18 c2 00 80 18 c2  .........@......
    02 00 02 00 ad 4e ad de ff ff ff ff ff ff ff ff  .....N..........
  backtrace:
    [<08cbd8bc>] iommu_domain_alloc+0x24/0x50
    [<b835abee>] arm_iommu_create_mapping+0xe4/0x134
    [<3acd268d>] arch_setup_dma_ops+0x4c/0x104
    [<9f7d2cce>] of_dma_configure+0x19c/0x3a4
    [<ba07704b>] really_probe+0xb0/0x47c
    [<4f510e4f>] driver_probe_device+0x78/0x1c4
    [<7481a0cf>] device_driver_attach+0x58/0x60
    [<0ff8f5c1>] __driver_attach+0xb8/0x158
    [<86006144>] bus_for_each_dev+0x74/0xb4
    [<10159dca>] bus_add_driver+0x1c0/0x200
    [<8a265265>] driver_register+0x74/0x108
    [<e0f3451a>] exynos_drm_init+0xb0/0x134
    [<db3fc7ba>] do_one_initcall+0x90/0x458
    [<6da35917>] kernel_init_freeable+0x188/0x200
    [<db3f74d4>] kernel_init+0x8/0x110
    [<1f3cddf9>] ret_from_fork+0x14/0x20
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>