drm/i915/gen9+: Use for_each_intel_plane_on_crtc in skl_print_wm_changes, v2.

drm/i915/gen9+: Use for_each_intel_plane_on_crtc in skl_print_wm_changes, v2.

Using for_each_intel_plane_on_crtc will allow us to find all allocations
that may have changed, not just the one added by the atomic state.

This will print changes to plane allocations for crtc's when some
planes are not added to the atomic state.

Changes since v1:
- Rephrase commit message. (Ville)
- Use plane->base.id and plane->name to kill off cursor special
  case. (Ville)
- Add intel_crtc to prevent a line wrap. (Paulo)
- Line wrap debug messages.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/c9f7dc1a-d23a-7c16-b2b7-1c23dd07ed35@linux.intel.com
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>