The switch to the generic dma ops made dma masks mandatory, breaking
devices having them not set. In case of bcm63xx, it broke ethernet with
the following warning when trying to up the device:

[    2.633123] ------------[ cut here ]------------
[    2.637949] WARNING: CPU: 0 PID: 325 at ./include/linux/dma-mapping.h:516 bcm_enetsw_open+0x160/0xbbc
[    2.647423] Modules linked in: gpio_button_hotplug
[    2.652361] CPU: 0 PID: 325 Comm: ip Not tainted 4.19.16 #0
[    2.658080] Stack : 80520000 804cd3ec 00000000 00000000 804ccc00 87085bdc 87d3f9d4 804f9a17
[    2.666707]         8049cf18 00000145 80a942a0 00000204 80ac0000 10008400 87085b90 eb3d5ab7
[    2.675325]         00000000 00000000 80ac0000 000022b0 00000000 00000000 00000007 00000000
[    2.683954]         0000007a 80500000 0013b381 00000000 80000000 00000000 804a1664 80289878
[    2.692572]         00000009 00000204 80ac0000 00000200 00000002 00000000 00000000 80a90000
[    2.701191]         ...
[    2.703701] Call Trace:
[    2.706244] [<8001f3c8>] show_stack+0x58/0x100
[    2.710840] [<800336e4>] __warn+0xe4/0x118
[    2.715049] [<800337d4>] warn_slowpath_null+0x48/0x64
[    2.720237] [<80289878>] bcm_enetsw_open+0x160/0xbbc
[    2.725347] [<802d1d4c>] __dev_open+0xf8/0x16c
[    2.729913] [<802d20cc>] __dev_change_flags+0x100/0x1c4
[    2.735290] [<802d21b8>] dev_change_flags+0x28/0x70
[    2.740326] [<803539e0>] devinet_ioctl+0x310/0x7b0
[    2.745250] [<80355fd8>] inet_ioctl+0x1f8/0x224
[    2.749939] [<802af290>] sock_ioctl+0x30c/0x488
[    2.754632] [<80112b34>] do_vfs_ioctl+0x740/0x7dc
[    2.759459] [<80112c20>] ksys_ioctl+0x50/0x94
[    2.763955] [<800240b8>] syscall_common+0x34/0x58
[    2.768782] ---[ end trace fb1a6b14d74e28b6 ]---
[    2.773544] bcm63xx_enetsw bcm63xx_enetsw.0: cannot allocate rx ring 512

Fix this by adding appropriate DMA masks for the platform devices.

Fixes: f8c55dc6 ("MIPS: use generic dma noncoherent ops for simple noncoherent platforms")
Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: stable@vger.kernel.org # v4.19+