scsi: mpi3mr: Support for preallocation of SGL BSG data buffers part-2

The driver acquires the required SGLs from the pre-allocated pool.
Co-developed-by: Sathya Prakash <sathya.prakash@broadcom.com>
Signed-off-by: Sathya Prakash <sathya.prakash@broadcom.com>
Signed-off-by: Chandrakanth patil <chandrakanth.patil@broadcom.com>
Link: https://lore.kernel.org/r/20231205191630.12201-3-chandrakanth.patil@broadcom.comSigned-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/mpi3mr/mpi3mr.h

@@ -247,6 +247,8 @@ struct mpi3mr_buf_map {
 	u32 kern_buf_len;
 	dma_addr_t kern_buf_dma;
 	u8 data_dir;
+	u16 num_dma_desc;
+	struct dma_memory_desc *dma_desc;
 };
 
 /* IOC State definitions */