dt-bindings: pinctrl: bcm2835-gpio: Add generic pinctrl support

Added generic pin configuration and multiplexing support,
and should be preferred than brcm legacy one.
Signed-off-by: Matheus Castello <matheus@castello.eng.br>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/pinctrl/brcm,bcm2835-gpio.txt

@@ -36,6 +36,24 @@ listed. In other words, a subnode that lists only a mux function implies no
 information about any pull configuration. Similarly, a subnode that lists only
 a pul parameter implies no information about the mux function.
 
+The BCM2835 pin configuration and multiplexing supports the generic bindings.
+For details on each properties, you can refer to ./pinctrl-bindings.txt.
+
+Required sub-node properties:
+  - pins
+  - function
+
+Optional sub-node properties:
+  - bias-disable
+  - bias-pull-up
+  - bias-pull-down
+  - output-high
+  - output-low
+
+Legacy pin configuration and multiplexing binding:
+*** (Its use is deprecated, use generic multiplexing and configuration
+bindings instead)
+
 Required subnode-properties:
 - brcm,pins: An array of cells. Each cell contains the ID of a pin. Valid IDs
   are the integer GPIO IDs; 0==GPIO0, 1==GPIO1, ... 53==GPIO53.