scsi: ufs: mcq: Add definition for REG_UFS_MEM_CFG register

scsi: ufs: mcq: Add definition for REG_UFS_MEM_CFG register

Instead of hardcoding the register field, add the proper definition. While
at it, let's also use ufshcd_rmwl() to simplify updating this register.

Reviewed-by: Peter Wang <peter.wang@mediatek.com>
Signed-off-by: ChanWoo Lee <cw9316.lee@samsung.com>
Link: https://lore.kernel.org/r/20240102014222.23351-1-cw9316.lee@samsung.com
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>