drm/i915/dp: Use a mode's crtc_clock vs. clock during state computation

drm/i915/dp: Use a mode's crtc_clock vs. clock during state computation

The encoder state computation should use the
drm_display_mode::crtc_clock member, instead of the clock member, the
former one possibly having a necessary adjustment wrt. to the latter
due to driver specific constraints. In practice the two values should
not differ at spots changed in this patch, since only MSO and 3D modes
would make them different, neither MSO or 3D relevant here, but still
use the expected crtc_clock version for consistency.

Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20251215192357.172201-6-imre.deak@intel.com