wifi: iwlwifi: mvm: fix ptk_pn memory leak

If adding a key to firmware fails we leak the allocated ptk_pn.
This shouldn't happen in practice, but we should still fix it.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230414130637.99446ffd02bc.I82a2ad6ec1395f188e0a1677cc619e3fcb1feac9@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>