perf/x86/rapl: Fix error handling in init_rapl_pmus()

If init_rapl_pmu() fails while allocating memory for "rapl_pmu" objects,
we miss freeing the "rapl_pmus" object in the error path. Fix that.

Fixes: 9b99d65c ("perf/x86/rapl: Move the pmu allocation out of CPU hotplug")
Signed-off-by: Dhananjay Ugwekar <dhananjay.ugwekar@amd.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250320100617.4480-1-dhananjay.ugwekar@amd.com