x86: PAT: fix address types in track_pfn_vma_new()

Impact: cleanup, fix warning

This warning:

 arch/x86/mm/pat.c: In function track_pfn_vma_copy:
 arch/x86/mm/pat.c:701: warning: passing argument 5 of follow_phys from incompatible pointer type

Triggers because physical addresses are resource_size_t, not u64.

This really matters when calling an interface like follow_phys() which
takes a pointer to a physical address -- although on x86, being
littleendian, it would generally work anyway as long as the memory region
wasn't completely uninitialized.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>