Passing the reference "struct kvm_pmc *pmc" when creating
pmc->perf_event is sufficient. This change helps to simplify the
calling convention by replacing reprogram_{gp, fixed}_counter()
with reprogram_counter() seamlessly.

No functional change intended.
Signed-off-by: Like Xu <likexu@tencent.com>
Message-Id: <20220518132512.37864-5-likexu@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>