Depending on the physical memory layout, some PCI MEM areas are not
usable. According to the SH7786 datasheet, the PCI MEM area from
1000_0000 to 13FF_FFFF is only usable if the physical memory layout
(in MMSELR) is 1, 2, 5 or 6. In all other configurations, this PCI MEM
area is not usable (because it overlaps with DRAM).

Therefore, this commit adjusts the PCI SH7786 initialization to mark
the relevant PCI resource as IORESOURCE_DISABLED if we can't use it.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Rich Felker <dalias@libc.org>