drm/i915/cx0: Track the C20 PHY VDR state in the PLL state

drm/i915/cx0: Track the C20 PHY VDR state in the PLL state

The Cx0 PLL enable programming needs to know if the PLL is in DP or HDMI
mode. The PLL manager framework doesn't pass the CRTC state to the PLL's
enable hook, so prepare here for the conversion to use the PLL manager
for Cx0 PHY PLLs by tracking the DP/HDMI mode in the PLL state.

This change has the advantage, that the VDR HW/SW state can be verified
now.

A follow up change will convert the PLL enable function to retrieve the
DP/HDMI mode parameter from the PLL state.

This also allows dropping the is_dp and port clock params from the
intel_c20_pll_program() function, since it can retrieve these now from
the PLL state.

v2: Fix comment to under same multicomment line (Suraj)

Signed-off-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://lore.kernel.org/r/20251117104602.2363671-6-mika.kahola@intel.com