[SCSI] bnx2fc: support software fcoe target

Software FCoE target always advertises RETRY bit even when there are no
tape LUNs behind the target. This causes the driver to enable FW support
for sequence level error recovery and perform REC/SRR. This patch
arrests the behavior by not enabling SLER feature for this target.

Signed-off-by: Bhanu Prakash Gollapudi <bprakash@broadcom.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>