perf/arm-cmn: Clean up unnecessary NUMA_NO_NODE check

Checking for NUMA_NO_NODE is a misleading and, on reflection, entirely
unnecessary micro-optimisation. If it ever did happen that an incoming
CPU has no NUMA affinity while the current CPU does, a questionably-
useful PMU migration isn't the biggest thing wrong with that picture...

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/00634da33c21269a00844140afc7cc3a2ac1eb4d.1725474584.git.robin.murphy@arm.com


Signed-off-by: Will Deacon <will@kernel.org>