No reason to restrict CDB size to 12 bytes in fcoe, so
increased to 16 so that 16 bytes SCSI CDB doesn't fail.

Uses common define to set max_cmd_len for fcoe and fnic,
fnic is already setting max_cmd_len to 16.

sg_readcap -l fails without this fix.
Signed-off-by: NVasu Dev <vasu.dev@intel.com>
Signed-off-by: NRobert Love <robert.w.love@intel.com>
Signed-off-by: NJames Bottomley <James.Bottomley@suse.de>