sfc: Clean up LED control

Reinitialise LEDs after overriding them for identification.

Rename set_fault_led method to set_id_led since we always use it for
NIC identification and not faults.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>