KVM: selftests: Report enable_pmu module value when test is skipped

Running x86_64/pmu_event_filter_test or x86_64/vmx_pmu_caps_test
with enable_pmu globally disabled will report the following into:
	1..0 # SKIP - Requirement not met: use_intel_pmu() || use_amd_pmu()
or
	1..0 # SKIP - Requirement not met: kvm_cpu_has(X86_FEATURE_PDCM)
this can be confusing, so add a check on kvm.enable_pmu.

Signed-off-by: Like Xu <likexu@tencent.com>
Link: https://lore.kernel.org/r/20230313085311.25327-3-likexu@tencent.com


Signed-off-by: Sean Christopherson <seanjc@google.com>