scsi: ufs: ufshpb: Fix possible memory leak

When HPB pinned region exists and mctx allocation for this region fails, a
memory leak is possible because memory is not released for the subregion
table of the current region.

Free memory for the subregion table of the current region.

Link: https://lore.kernel.org/r/1891546521.01629711601304.JavaMail.epsvc@epcpadp3


Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Keoseong Park <keosung.park@samsung.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>