drm/i915/cdclk: Remove the hardcoded divider from cdclk_compute_crawl_and_squash_midp...

drm/i915/cdclk: Remove the hardcoded divider from cdclk_compute_crawl_and_squash_midpoint()

cdclk_compute_crawl_and_squash_midpoint() was still assuming
that cd2x divider == 1 (ie. full divider == 2). Remove that
assumption by computing the dividers properly.

We'll also toss in a WARN in case the divider somehow ends
up different between the old and new cdclk configs. That should
never happen given we have div==2 in all the cdclk table entries
for the affected platforms.

If in the future we need a config where the divider also needs
to be changed then we likely need to add an extra step into the
cdclk programming sequence to make sure things stay within
legal limits throughout the process.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240207013334.29606-4-ville.syrjala@linux.intel.com
Reviewed-by: Gustavo Sousa <gustavo.sousa@intel.com>