x86/pmu: Report SKIP when testing Intel LBR on AMD platforms

The test conclusion of running Intel LBR on AMD platforms
should not be PASS, but SKIP, fix it.

Signed-off-by: Like Xu <likexu@tencent.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221102225110.3023543-5-seanjc@google.com