drm/vmwgfx: Don't look at state->allow_modeset

That's purely for the uapi layer to implement the ALLOW_MODESET flag.

Drivers should instead look at the state, e.g. through
drm_atomic_crtc_needs_modeset(), which vmwgfx already does. Also remove
the confusing comment, since checking allow_modeset is at best a micro
optimization.

v2: Rebase

Reviewed-by: Deepak Rawat <drawat@vmware.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: VMware Graphics <linux-graphics-maintainer@vmware.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190520223500.6032-1-daniel.vetter@ffwll.ch

drivers/gpu/drm/vmwgfx/vmwgfx_kms.c

@@ -1704,14 +1704,6 @@ vmw_kms_atomic_check_modeset(struct drm_device *dev,
 	if (ret)
 		return ret;
 
-	if (!state->allow_modeset)
-		return ret;
-
-	/*
-	 * Legacy path do not set allow_modeset properly like
-	 * @drm_atomic_helper_update_plane, This will result in unnecessary call
-	 * to vmw_kms_check_topology. So extra set of check.
-	 */
 	for_each_new_crtc_in_state(state, crtc, crtc_state, i) {
 		if (drm_atomic_crtc_needs_modeset(crtc_state))
 			need_modeset = true;