ARM: ux500: Disable the MMCI gpio-regulator by default

Not all supported boards will require a MMCI gpio-regulator,
therefore it's a good idea to only enable the node when and if
it is required. Let's disable it by default.
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

arch/arm/boot/dts/dbx5x0.dtsi

@@ -642,6 +642,8 @@ vmmci: regulator-gpio {
 			gpio-enable = <&tc3589x_gpio 17 0x4>;
 			states = <1800000 0x1
 				  2900000 0x0>;
+
+			status = "disabled";
 		};
 	};
 };