drm/i915: s/init_cdclk/init_cdclk_hw/

Give the cdclk init/uninit functions a _hw suffix to make
it clear they are about initializing the actual hardware.
I'll be wanting to to add a intel_cdclk_init() which is
purely initializing software structures.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200120174728.21095-12-ville.syrjala@linux.intel.com


Reviewed-by: Imre Deak <imre.deak@intel.com>