arm64: dts: imx8mp-beacon: Enable DW HDMI Bridge

There is a second HDMI connector on the baseboard which is routed
to the DW HDMI bridge through the PVI to the LCDIF3 and requires the
HDMI PHY to be enabled too.

Signed-off-by: Adam Ford <aford173@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>