ARM: dts: imx7-colibri: move and rename USB Host power regulator

The Colibri default which enables USB Host power is not necessarily
tied to the OTG2 controller, some carrier board use the pin to
control USB power for both controllers. Hence name the pinctrl
group more generic.

Also move the regulator to the generic eval-v3 device tree since
the regulator is always on the carrier board. In the Colibri iMX7S
case the regulator is just not used.  This allows to reuse the
regulator in a upcoming SKU Colibri iMX7D 1GB with eMMC.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>