ARM: CSR: extend the compatibility of gpio controller to pinmux in dts

gpio controller handles the switch of gpio and pinmux. And drivers/pinctrl/pinmux-sirf.c
will contain both gpio and pinmux.

Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Barry Song <Baohua.Song@csr.com>

arch/arm/boot/dts/prima2-cb.dts

@@ -279,7 +279,7 @@
 			gpio: gpio-controller@b0120000 {
 				#gpio-cells = <2>;
 				#interrupt-cells = <2>;
-				compatible = "sirf,prima2-gpio";
+				compatible = "sirf,prima2-gpio-pinmux";
 				reg = <0xb0120000 0x10000>;
 				gpio-controller;
 				interrupt-controller;