[ARM] 5435/1: fix compile warning in sanity_check_meminfo()

Compiling recent 2.6.29-rc kernels for ARM gives me the following warning:

arch/arm/mm/mmu.c: In function 'sanity_check_meminfo':
arch/arm/mm/mmu.c:697: warning: comparison between pointer and integer

This is because commit 3fd9825c


"[ARM] 5402/1: fix a case of wrap-around in sanity_check_meminfo()"
in 2.6.29-rc5-git4 added a comparison of a pointer with PAGE_OFFSET,
which is an integer.

Fixed by casting PAGE_OFFSET to void *.

Signed-off-by: Mikael Pettersson <mikpe@it.uu.se>
Acked-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>