[SCSI] libfcoe: change fip_select to return new FCF

Neaten several calls to fip_select() by having it return the
pointer to the new FCF.

Signed-off-by: Joe Eykholt <jeykholt@cisco.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>