Add support for completing requests from Completion Queue.  Some host
controllers support vendor specific registers that provide a bitmap of all
CQs which have at least one completed CQE. Add this support.  The MCQ
specification doesn't provide the Task Tag or its equivalent in the
Completion Queue Entry.  So use an indirect method to find the Task Tag
from the Completion Queue Entry.
Co-developed-by: Can Guo <quic_cang@quicinc.com>
Signed-off-by: Can Guo <quic_cang@quicinc.com>
Signed-off-by: Asutosh Das <quic_asutoshd@quicinc.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>