drm/i915: Kill off intel_crtc->atomic.wait_vblank, v6.

Currently we perform our own wait in post_plane_update,
but the atomic core performs another one in wait_for_vblanks.
This means that 2 vblanks are done when a fb is changed,
which is a bit overkill.

Merge them by creating a helper function that takes a crtc mask
for the planes to wait on.

The broadwell vblank workaround may look gone entirely but this is
not the case. pipe_config->wm_changed is set to true
when any plane is turned on, which forces a vblank wait.

Changes since v1:
- Removing the double vblank wait on broadwell moved to its own commit.
Changes since v2:
- Move out POWER_DOMAIN_MODESET handling to its own commit.
Changes since v3:
- Do not wait for vblank on legacy cursor updates. (Ville)
- Move broadwell vblank workaround comment to page_flip_finished. (Ville)
Changes since v4:
- Compile fix, legacy_cursor_flip -> *_update.
Changes since v5:
- Kill brackets.
- Add WARN_ON when wait_for_vblanks fails.
- Remove extra newlines.
- Split the checks whether vblank is needed to a separate function,
  with comments why a vblank is needed.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/56CD84DA.5030507@linux.intel.com
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 4852049..3530166 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -379,6 +379,7 @@
 	bool update_pipe; /* can a fast modeset be performed? */
 	bool disable_cxsr;
 	bool wm_changed; /* watermarks are updated */
+	bool fb_changed; /* fb on any of the planes is changed */
 
 	/* Pipe source size (ie. panel fitter input size)
 	 * All planes will be positioned inside this space,
@@ -547,7 +548,6 @@
 
 	/* Sleepable operations to perform after commit */
 	unsigned fb_bits;
-	bool wait_vblank;
 	bool post_enable_primary;
 	unsigned update_sprite_watermarks;