iomem_is_exclusive() requires a CPU physical address, but on some arches we
supplied a PCI bus address instead.

On most arches, pci_resource_to_user(res) returns "res->start", which is a
CPU physical address.  But on microblaze, mips, powerpc, and sparc, it
returns the PCI bus address corresponding to "res->start".

The result is that pci_mmap_resource() may fail when it shouldn't (if the
bus address happens to match an existing resource), or it may succeed when
it should fail (if the resource is exclusive but the bus address doesn't
match it).

Call iomem_is_exclusive() with "res->start", which is always a CPU physical
address, not the result of pci_resource_to_user().

Fixes: e8de1481 ("resource: allow MMIO exclusivity for device drivers")
Suggested-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Arjan van de Ven <arjan@linux.intel.com>