scsi: fnic: Fix missing DMA mapping error in fnic_send_frame()

scsi: fnic: Fix missing DMA mapping error in fnic_send_frame()

dma_map_XXX() can fail and should be tested for errors with
dma_mapping_error().

Fixes: a63e78eb2b0f ("scsi: fnic: Add support for fabric based solicited requests and responses")
Signed-off-by: Thomas Fourier <fourier.thomas@gmail.com>
Link: https://lore.kernel.org/r/20250618065715.14740-2-fourier.thomas@gmail.com
Reviewed-by: Karan Tilak Kumar <kartilak@cisco.com>
Reviewed-by: John Menghini <jmeneghi@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>