drm/i915: Use a plain old int for the cdclk/mdclk ratio

No point in throwing around u8 when we're dealing with
just an integer. Use a plain old boring 'int'.

Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Gustavo Sousa <gustavo.sousa@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240402155016.13733-14-ville.syrjala@linux.intel.com