x86: PAT documentation updates with debug info

Documentation update for PAT. Reflect the latest API details.
Also, adds details about ways to get more info in order to debug PAT.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
1 file changed