KVM: SVM: Clean up macros related to architectural MSRPM definitions

KVM: SVM: Clean up macros related to architectural MSRPM definitions

Move SVM's MSR Permissions Map macros to svm.h in anticipation of adding
helpers that are available to SVM code, and opportunistically replace a
variety of open-coded literals with (hopefully) informative macros.

Opportunistically open code ARRAY_SIZE(msrpm_ranges) instead of wrapping
it as NUM_MSR_MAPS, which is an ambiguous name even if it were qualified
with "SVM_MSRPM".

Deliberately leave the ranges as open coded literals, as using macros to
define the ranges actually introduces more potential failure points, since
both the definitions and the usage have to be careful to use the correct
index.  The lack of clear intent behind the ranges will be addressed in
future patches.

No functional change intended.

Link: https://lore.kernel.org/r/20250610225737.156318-10-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>