drm/vmwgfx: Stop updating plane->fb

We want to get rid of plane->fb on atomic drivers. Stop setting it.

Cc: Deepak Rawat <drawat@vmware.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Cc: Sinclair Yeh <syeh@vmware.com>
Cc: VMware Graphics <linux-graphics-maintainer@vmware.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Deepak Rawat <drawat@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180525185045.29689-5-ville.syrjala@linux.intel.com
Reviewed-by: Sinclair Yeh <syeh@vmware.com>

drivers/gpu/drm/vmwgfx/vmwgfx_scrn.c

@@ -525,8 +525,6 @@ vmw_sou_primary_plane_atomic_update(struct drm_plane *plane,
 		 */
 		if (ret != 0)
 			DRM_ERROR("Failed to update screen.\n");
-
-		crtc->primary->fb = plane->state->fb;
 	} else {
 		/*
 		 * When disabling a plane, CRTC and FB should always be NULL

drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c

@@ -1285,8 +1285,6 @@ vmw_stdu_primary_plane_atomic_update(struct drm_plane *plane,
 							 1, 1, NULL, crtc);
 		if (ret)
 			DRM_ERROR("Failed to update STDU.\n");
-
-		crtc->primary->fb = plane->state->fb;
 	} else {
 		crtc = old_state->crtc;
 		stdu = vmw_crtc_to_stdu(crtc);