drm/i915: Collect more cdclk state under the same roof

Move the min_cdclk[] and min_voltage_level[] arrays under the
rest of the cdclk state. And while at it provide a simple
helper (intel_cdclk_clear_state()) to clear the state during
the ww_mutex backoff dance.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200120174728.21095-6-ville.syrjala@linux.intel.com


Reviewed-by: José Roberto de Souza <jose.souza@intel.com>