ARM: dts: imx6qdl-vicut1/victgo: Remove UART2

Only first prototype had UART2 and there are no plans to add it in the
future.

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