scsi: ufs: ufs-qcom: Use bitfields where appropriate

Use bitfield macros where appropriate to simplify the driver.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Asutosh Das <quic_asutoshd@quicinc.com>
Tested-by: Andrew Halaney <ahalaney@redhat.com> # Qdrive3/sa8540p-ride
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>