Add a debugfs interface to list out all the PAT memtype reservations.
Appears at debugfs x86/pat_memtype_list and output format is
type @ <start addr>-<end addr>

We do not hold the lock while printing the entire list. So, the list may not be
a consistent copy in case where regions are getting added or deleted
at the same time.
Signed-off-by: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>