Add pinctl support for the SAM UART and SAM USART devices. We update
the UART and USART bindings to have pinctrl-0 bindings that are expected
to have 2 phandles to the RX & TX pinctrl nodes.
The pinctrl nodes will have an 'atmel,pins' property that describes the
GPIO port, pin and periphal configuration for that pin.
We add sam*-pinctrl.dtsi files with all the various pin ctrl
configuration operations supported by the given SoC family. These
files are based on data extracted from the Atmel ASF HAL
(in include/sam<FAMILY>/pio/*.h).
Signed-off-by: Kumar Gala <kumar.gala@linaro.org>
Kumar Gala