scsi: qedi: add module param to set ping packet size

Default packet size is 0x400. For jumbo packets set to 0x2400.

Signed-off-by: Nilesh Javali <nilesh.javali@cavium.com>
Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>