perf/x86/rapl: Rename rapl_pmu variables

Rename struct rapl_pmu variables from "pmu" to "rapl_pmu", to
avoid any confusion between the variables of two different
structs pmu and rapl_pmu. As rapl_pmu also contains a pointer to
struct pmu, which leads to situations in code like pmu->pmu,
which is needlessly confusing. Above scenario is replaced with
much more readable rapl_pmu->pmu with this change.

Also rename "pmus" member in rapl_pmus struct, for same reason.

No functional change.

Signed-off-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: "Gautham R. Shenoy" <gautham.shenoy@amd.com>
Reviewed-by: Zhang Rui <rui.zhang@intel.com>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20241115060805.447565-5-Dhananjay.Ugwekar@amd.com