arm64: dts: apq8096-db820c: Add HDMI display support
The APQ8096 DB820c platform provides HDMI output. The MDSS block on
8x96 supports a direct HDMI out. Populate the MDSS, MDP and HDMI DT
nodes. Also, add the HDMI HPD and DDC pinctrl nodes with the bias
and driver strength specified for this platform.