scsi: mpi3mr: Support for preallocation of SGL BSG data buffers part-1

scsi: mpi3mr: Support for preallocation of SGL BSG data buffers part-1

The driver now supports SGLs for BSG data transfer. Upon loading, the
driver pre-allocates SGLs in chunks of 8k, results in a total of 256 * 8k,
equal to 2MB. These pre-allocated SGLs are reserved for handling BSG
commands and are deallocated during driver unload.

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/20231205191630.12201-2-chandrakanth.patil@broadcom.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>