ARM: dts: imx6qp: prtwd3: Enable USB over current detection on USB OTG port

The imx6qp-prtwd3 board supports USB over current detection on the USB
OTG port, however, it was previously disabled in the device tree. This
commit enables the over current detection by changing the device tree
setting from 'disable-over-current' to 'over-current-active-low'. This
could potentially protect the USB port from damage due to over current
situations.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>