scsi: ufs: Clean up some rpm/spm level SysFS nodes upon remove

When reloading module these two attributes aren't cleaned up properly
and they persist causing warnings when trying to load module
again. Additionally they are not recreated properly due to that.

Signed-off-by: Michał Potomski <michalx.potomski@intel.com>
Reviewed-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>