drm/i915/dp: Set min_bpp limit to 30 in HDR mode

drm/i915/dp: Set min_bpp limit to 30 in HDR mode

Update intel_dp_compute_config_limits() to use a minimum of
30 bits per pixel when the connector is in HDR mode
(specifically, when EOTF is SMPTE ST2084), aligning with HDR
display requirements.

To support this, the function now takes a drm_connector_state
instead of an intel_connector, and the required updates are
made in all call sites, including MST handling.

This ensures sufficient bitdepth for HDR content to avoid
banding.

If the required bandwidth for 30 bpp cannot be supported,
the driver will either fall back to DSC or reject the mode
during atomic check if DSC is not supported.

Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://lore.kernel.org/r/20250730055523.2214966-3-chaitanya.kumar.borah@intel.com