fixed generic page.h for non-zero PAGE_OFFSET
fixed generic page.h for non-zero PAGE_OFFSET

asm-generic/page.h had several problems when used with a non-zero PAGE_OFFSET.
This patch adds a default ARCH_PFN_OFFSET and fixes the __va, __pa, and
pfn_valid macros to work with non-zero PAGE_OFFSETs.

Signed-off-by: Mark Salter <3186038803479a476d7152f26680d7b1b21c12c4@redhat.com>
Acked-by: Arnd Bergmann <f2c659f01951776204a6c5b902787d9019fbeebd@arndb.de>

KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas