scsi: ufs: host: mediatek: Fix unbalanced IRQ enable issue

Resolve the issue of unbalanced IRQ enablement by setting the
'is_mcq_intr_enabled' flag after the first successful IRQ enablement.
Ensure proper tracking of the IRQ state and prevent potential mismatches
in IRQ handling.

Signed-off-by: Peter Wang <peter.wang@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>