drm/i915: Pass crtc state to modeset_get_crtc_power_domains.

drm/i915: Pass crtc state to modeset_get_crtc_power_domains.

Use our newly created encoder_mask to iterate over the encoders.
This makes it possible to get the crtc power domains from the
crtc_state at any time, without any locks or having to look at
the legacy state.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1455108583-29227-2-git-send-email-maarten.lankhorst@linux.intel.com
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>