microblaze: Fix sparse warning - fault.c

Warning log:
CHECK   arch/microblaze/mm/fault.c
arch/microblaze/mm/fault.c:51:6: warning: incorrect type in initializer (different address spaces)
arch/microblaze/mm/fault.c:51:6:    expected unknown type 2const [noderef] *__gu_addr<asn:1>
arch/microblaze/mm/fault.c:51:6:    got unsigned int *<noident>
arch/microblaze/mm/fault.c:68:6: warning: symbol 'bad_page_fault' was not declared. Should it be static?

Signed-off-by: Michal Simek <monstr@monstr.eu>