perf/x86/rapl: Remove the global variable rapl_msrs

Prepare for the addition of RAPL core energy counter support.

After making the rapl_model struct global, the rapl_msrs global
variable isn't needed, so remove it.

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/20241115060805.447565-9-Dhananjay.Ugwekar@amd.com