[libata] ahci: correct enclosure LED state save

ahci_transmit_led_message saves off the led_state
with a value that includes the port number OR'd
in, this incorrect value maybe reported back
in ahci_led_store.

For instance, if you turn off all the leds for
port 1 and cat the value back it will report 1
instead of 0.

# echo 0 > /sys/class/scsi_host/host1/em_message
# cat /sys/class/scsi_host/host1/em_message
1

Signed-off-by: David Milburn <dmilburn@redhat.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>