x86: pat: Clean up req_type special case for reserve_memtype()

Commit:

  b6ff32d9

: x86, PAT: Consolidate code in pat_x_mtrr_type() and reserve_memtype()

consolidated code in pat_x_mtrr_type() and reserve_memtype(),
which removed the special case (req_type is -1) for the
PAT-enabled part.

We should also change comments and the PAT-disabled part.

Signed-off-by: Xiaotian Feng <dfeng@redhat.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
LKML-Reference: <1257844987-7906-1-git-send-email-dfeng@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>