x86/pmu: Introduce multiple_{one, many}() to improve readability

The current measure_one() forces the common case to pass in unnecessary
information in order to give flexibility to a single use case. It's just
syntatic sugar, but it really does help readers as it's not obvious that
the "1" specifies the number of events, whereas multiple_many() and
measure_one() are relatively self-explanatory.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Like Xu <likexu@tencent.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221102225110.3023543-8-seanjc@google.com