drm/tegra: sor: Use sor1_src clock to set parent for HDMI

When running in HDMI mode, the sor1 IP block needs to use the sor1_src
as parent clock, and in turn configure the sor1_src to use pll_d2_out0
as its parent.

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