pinctrl: meson: Add GXL pinctrl definitions

Add support for the Amlogic Meson GXL SoC, this is a partially complete
definition only based on the Amlogic Vendor tree.

This definition differs a lot from the GXBB and needs a separate entry.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>