Use __free(device_node) cleanup attribute for domains_node and add
missing of_node_put(np_pmu) calls in error paths to prevent device
node reference leaks.

* Would scope-based resource management become relevant for both local variables?

* See also once more:
  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/stable-kernel-rules.rst?h=v6.19-rc7#n34


Regards,
Markus