ARM: dts: imx6qdl-cubox-i: update GPIO specification

Fabio Estevam suggested using GPIO_ACTIVE_HIGH in the gpio specification
for the USB regulators.  Change them to conform.

Suggested-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>