In MTRR code use_intel() is only used in one source file, and the
relevant use_intel_if member of struct mtrr_ops is set only in
generic_mtrr_ops.

Replace use_intel() with a single flag in cacheinfo.c which can be
set when assigning generic_mtrr_ops to mtrr_if. This allows to drop
use_intel_if from mtrr_ops, while preparing to decouple PAT from MTRR.
As another preparation for the PAT/MTRR decoupling use a bit for MTRR
control and one for PAT control. For now set both bits together, this
can be changed later.

As the new flag will be set only if mtrr_enabled is set, the test for
mtrr_enabled can be dropped at some places.

  [ bp: Massage commit message. ]
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20221102074713.21493-4-jgross@suse.comSigned-off-by: Borislav Petkov <bp@suse.de>