scsi: ufs: ufshpb: Fix a NULL check on list iterator

The list iterator is always non-NULL so the check 'if (!rgn)' is always
false and the dev_err() is never called. Move the check outside the loop
and determine if 'victim_rgn' is NULL, to fix this bug.

Link: https://lore.kernel.org/r/20220320150733.21824-1-xiam0nd.tong@gmail.com
Fixes: 4b5f4907

 ("scsi: ufs: ufshpb: L2P map management for HPB read")
Reviewed-by: Daejun Park <daejun7.park@samsung.com>
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>