selftests, kvm: Replace manual MSR defs with common msr-index.h

The kernel's version of msr-index.h was pulled wholesale into tools by
commit

  444e2ff3 ("tools arch x86: Grab a copy of the file containing the MSR numbers"),

Use the common msr-index.h instead of manually redefining everything in
a KVM-only header.

Note, a few MSR-related definitions remain in processor.h because they
are not covered by msr-index.h, including the awesomely named
APIC_BASE_MSR, which refers to starting index of the x2APIC MSRs, not
the actual MSR_IA32_APICBASE, which *is* defined by msr-index.h.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20191221044513.21680-3-sean.j.christopherson@intel.com