ARM: dts: imx6ull-colibri: fix vqmmc regulator

The correct spelling for the property is gpios. Otherwise, the regulator
will neither reserve nor control any GPIOs. Thus, any SD/MMC card which
can use UHS-I modes will fail.

Fixes: c2e4987e ("ARM: dts: imx6ull: add Toradex Colibri iMX6ULL support")
Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
Signed-off-by: Denys Drozdov <denys.drozdov@toradex.com>
Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>