attr_name_kobj's memory allocation is done with mutex_lock() held, this
is not needed.

Move allocation outside of mutex_lock() so unlock is not needed when
allocation fails.
Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20231113200742.3593548-2-harshit.m.mogalapalli@oracle.comSigned-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>