x86: PAT: implement track/untrack of pfnmap regions for x86 - v3

Impact: New mm functionality.

Hookup remap_pfn_range and vm_insert_pfn and corresponding copy and free
routines with reserve and free tracking.

reserve and free here only takes care of non RAM region mapping. For RAM
region, driver should use set_memory_[uc|wc|wb] to set the cache type and
then setup the mapping for user pte. We can bypass below
reserve/free in that case.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>