drm/i915: Move more cdclk state handling into the cdclk code

drm/i915: Move more cdclk state handling into the cdclk code

Move the initial setup of state->{cdclk,min_cdclk[],min_voltage_level[]}
into intel_modeset_calc_cdclk(), and we'll move the counterparts into
intel_cdclk_swap_state(). This encapsulates the cdclk state much better.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200120174728.21095-5-ville.syrjala@linux.intel.com
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>