gpio: aspeed: dt: Fix description alignment in bindings document

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/gpio/gpio-aspeed.txt

@@ -17,7 +17,7 @@ Required properties:
 
 Optional properties:
 
-- interrupt-parent     : The parent interrupt controller, optional if inherited
+- interrupt-parent      : The parent interrupt controller, optional if inherited
 
 The gpio and interrupt properties are further described in their respective
 bindings documentation: