ARM: shmobile: lager: Correct setting of ethernet PHY LED mode

The correct binding is "micrel,led-mode", not "led-mode".

This corrects an error which was introduced when setting of ethernet PHY
LED mode was added by 82e62182d59bd1d0 ("ARM: shmobile: lager: Set ethernet
PHY LED mode").

This makes the lager code consistent with the koelsch code which was added
by ae00d12a032490b3 ("ARM: shmobile: koelsch: Set ethernet PHY LED mode").

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>