scsi: ufs: core: Rename the MASK_TRANSFER_REQUESTS_SLOTS constant

Rename this constant to prepare for the introduction of the
MASK_TRANSFER_REQUESTS_SLOTS_MCQ constant. The acronym "SDB" stands for
"single doorbell" (mode).

Reviewed-by: Peter Wang <peter.wang@mediatek.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240708211716.2827751-5-bvanassche@acm.org


Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>