pinctrl: meson-gxl: Add Ethernet PHY LEDS pins

The Amlogic Meson GXL SoCs embeds an 10/100 Ethernet PHY, this patchs enables
the Link and Activity LEDs signals.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>