KVM: x86/vPMU: rename a few PMU functions

Before introducing a pmu.h header for them, make the naming more
consistent.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --cc arch/x86/include/asm/kvm_host.h
Simple merge

diff --cc arch/x86/kvm/cpuid.c
Simple merge

diff --cc arch/x86/kvm/pmu.c
Simple merge

diff --cc arch/x86/kvm/x86.c
Simple merge