[ARM] 4973/1: Tosa: use leds-gpio driver.

Now as the scoop pins are covered by the generic gpio API,
we can use leds-gpio driver instead of special leds-tosa.

Signed-off-by: Dmitry Baryshkov <dbaryshkov@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>