drm/i915: Extract icl_set_pipe_chicken()

We need configure PIPE_CHICKEN during fastboot as well. Let's extract
it to a helper.

v2: Apparently PIPE_CHICKEN is icl+ only

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190204202139.26884-1-ville.syrjala@linux.intel.com


Reviewed-by: Matt Roper <matthew.d.roper@intel.com>