ARM: dts: imx51-babbage: Make use of pinctrl_usbh1reg

Pinctrl_usbh1reg defines pinmux setting for reset GPIO used by
usbh1phy, but is not referenced by that node. Fix that.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>