drm/i915: rename modeset_update_power_wells

To modeset_update_crtc_power_domains, since this function is
responsible for updating all the power domains of all CRTCs after a
modeset. In the future we should also run this function on all
platforms, not just Haswell.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>