drm/vmwgfx: Fix F26 Wayland screen update issue

vmwgfx currently cannot support non-blocking commit because when
vmw_*_crtc_page_flip is called, drm_atomic_nonblocking_commit()
schedules the update on a thread.  This means vmw_*_crtc_page_flip
cannot rely on the new surface being bound before the subsequent
dirty and flush operations happen.

Cc: <stable@vger.kernel.org> # 4.12.x

Signed-off-by: Sinclair Yeh <syeh@vmware.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Charmaine Lee <charmainel@vmware.com>

drivers/gpu/drm/vmwgfx/vmwgfx_kms.c

@@ -1567,10 +1567,34 @@ vmw_kms_atomic_check_modeset(struct drm_device *dev,
 }
 
 
+/**
+ * vmw_kms_atomic_commit - Perform an atomic state commit
+ *
+ * @dev: DRM device
+ * @state: the driver state object
+ * @nonblock: Whether nonblocking behaviour is requested
+ *
+ * This is a simple wrapper around drm_atomic_helper_commit() for
+ * us to clear the nonblocking value.
+ *
+ * Nonblocking commits currently cause synchronization issues
+ * for vmwgfx.
+ *
+ * RETURNS
+ * Zero for success or negative error code on failure.
+ */
+int vmw_kms_atomic_commit(struct drm_device *dev,
+			  struct drm_atomic_state *state,
+			  bool nonblock)
+{
+	return drm_atomic_helper_commit(dev, state, false);
+}
+
+
 static const struct drm_mode_config_funcs vmw_kms_funcs = {
 	.fb_create = vmw_kms_fb_create,
 	.atomic_check = vmw_kms_atomic_check_modeset,
-	.atomic_commit = drm_atomic_helper_commit,
+	.atomic_commit = vmw_kms_atomic_commit,
 };
 
 static int vmw_kms_generic_present(struct vmw_private *dev_priv,