ARM: ep93xx: add LEDs and triggers to defconfig

The EP93xx has two designated LEDs (not always connected): a
green and a red one. These are registered in the core, so let's
enable the driver and some triggers.

Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>