drm/tegra: sor: Use correct power supply names for HDMI

The hardware documentation uses AVDD_IO_HDMI_DP and VDD_HDMI_DP_PLL to
denote the two power supplies that drive the HDMI/DP outputs of the SOR.
Use these names instead of the arbitrary AVDD_IO and VDD_PLL names that
were used previously to avoid confusion.

Signed-off-by: Thierry Reding <treding@nvidia.com>