[MIPS] Au1200: MMC resource size off by one

Au12x0 MMC platform device strangely claims 0x41 bytes for its
memory-mapped registers.  Make it claim the whole 0x80000 instead according
to the memory map given in the datasheets.

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>