scsi: ufs: core: Move an assignment in ufshcd_mcq_process_cqe()

scsi: ufs: core: Move an assignment in ufshcd_mcq_process_cqe()

Since 'tag' is only used inside the if-statement, move the 'tag'
assignment into the if-statement. This patch prepares for introducing a
WARN_ON_ONCE() call in ufshcd_mcq_get_tag() if the tag lookup fails.

Reviewed-by: Avri Altman <avri.altman@sandisk.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://patch.msgid.link/20251031204029.2883185-9-bvanassche@acm.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>