[NET] smc91x: provide configurable leds

This patch provides a mechanism for platforms to be able to supply the
LED configuration via platform data, rather than having to hard code
it in smc91x.h.

Acked-by: Eric Miao <eric.y.miao@gmail.com>
Acked-by: Nicolas Pitre <nico@cam.org>
Acked-by: Jeff Garzik <jgarzik@pobox.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>