scsi: fcoe: fix off by one in eth2fc_speed()

This should be "< ARRAY_SIZE()" instead of "<= ARRAY_SIZE()".

Fixes: 0b924e55 ("scsi: fcoe: provide translation table between Ethernet and FC port speeds")
Signed-off-by: Vincent Stehlé <vincent.stehle@laposte.net>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>