scsi: megaraid_sas: handle dma_addr_t right on 32-bit

When building with a dma_addr_t that is different from pointer size, we
get this warning:

drivers/scsi/megaraid/megaraid_sas_fusion.c: In function 'megasas_make_prp_nvme':
drivers/scsi/megaraid/megaraid_sas_fusion.c:1654:17: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]

It's better to not pretend that the dma address is a pointer and instead
use a dma_addr_t consistently.

Fixes: 33203bc4 ("scsi: megaraid_sas: NVME fast path io support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>