arm64: dts: imx8mm-venice-gw7901: add support for USB hub subload

The USB hub has it's reset as GPIO4_IO17 but can be sub-loaded and
VBUS provided by a VBUS regulator with GPIO4_IO2 as the enable and
GPIO1_IO15 as the active-low over-current.

Enable pull-up for GPIO4_IO17 to keep hub out of reset and move VBUS
enable to GPIO4_IO2. Additionally enable pull-up on GPIO1_IO15 so that
if the hub is loaded it never over-currents.

This allows USB to work in both configurations without a device-tree
change.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>