drm/i915/cdclk: Squash waveform is 16 bits

Have cdclk_squash_waveform() return a u16 since that's
how many bits we have in the waveform. We alreday use
u16 everywhere else.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240207013334.29606-3-ville.syrjala@linux.intel.com


Reviewed-by: Gustavo Sousa <gustavo.sousa@intel.com>