scsi: qla1280: Fix kernel oops when debug level > 2

scsi: qla1280: Fix kernel oops when debug level > 2

A null dereference or oops exception will eventually occur when qla1280.c
driver is compiled with DEBUG_QLA1280 enabled and ql_debug_level > 2.  I
think its clear from the code that the intention here is sg_dma_len(s) not
length of sg_next(s) when printing the debug info.

Signed-off-by: Magnus Lindholm <linmag7@gmail.com>
Link: https://lore.kernel.org/r/20250125095033.26188-1-linmag7@gmail.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>