scsi: qla2xxx: Fix DMA-API call trace on NVMe LS requests

The following message and call trace was seen with debug kernels:

DMA-API: qla2xxx 0000:41:00.0: device driver failed to check map
error [device address=0x00000002a3ff38d8] [size=1024 bytes] [mapped as
single]
WARNING: CPU: 0 PID: 2930 at kernel/dma/debug.c:1017
	 check_unmap+0xf42/0x1990

Call Trace:
	debug_dma_unmap_page+0xc9/0x100
	qla_nvme_ls_unmap+0x141/0x210 [qla2xxx]

Remove DMA mapping from the driver altogether, as it is already done by FC
layer. This prevents the warning.

Fixes: c85ab7d9

 ("scsi: qla2xxx: Fix missed DMA unmap for NVMe ls requests")
Cc: stable@vger.kernel.org
Signed-off-by: Arun Easi <aeasi@marvell.com>
Signed-off-by: Nilesh Javali <njavali@marvell.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>