dt-bindings: mmc: meson-gx: add reset

Add the reset to the documentation of the meson-gx mmc controller
bindings.

Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Documentation/devicetree/bindings/mmc/amlogic,meson-gx.txt

@@ -20,6 +20,7 @@ Required properties:
 	"clkin1" - Other parent clock of internal mux
   The driver has an internal mux clock which switches between clkin0 and clkin1 depending on the
   clock rate requested by the MMC core.
+- resets     : phandle of the internal reset line
 
 Example:
 
@@ -30,4 +31,5 @@ Example:
 		clocks = <&clkc CLKID_SD_EMMC_A>, <&xtal>, <&clkc CLKID_FCLK_DIV2>;
 		clock-names = "core", "clkin0", "clkin1";
 		pinctrl-0 = <&emmc_pins>;
+		resets = <&reset RESET_SD_EMMC_A>;
 	};