drm/nouveau/kms/nv50-: fix panel scaling

Under certain circumstances, encoder atomic_check() can be entered
without adjusted_mode having been reset to the same as mode, which
confuses the scaling logic and can lead to a misprogrammed display.

Fix this by checking against the user-provided mode directly.

Link: https://bugs.freedesktop.org/show_bug.cgi?id=108615
Link: https://gitlab.freedesktop.org/xorg/driver/xf86-video-nouveau/issues/464
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/dispnv50/disp.c

@@ -326,9 +326,9 @@ nv50_outp_atomic_check_view(struct drm_encoder *encoder,
 			 * same size as the native one (e.g. different
 			 * refresh rate)
 			 */
-			if (adjusted_mode->hdisplay == native_mode->hdisplay &&
-			    adjusted_mode->vdisplay == native_mode->vdisplay &&
-			    adjusted_mode->type & DRM_MODE_TYPE_DRIVER)
+			if (mode->hdisplay == native_mode->hdisplay &&
+			    mode->vdisplay == native_mode->vdisplay &&
+			    mode->type & DRM_MODE_TYPE_DRIVER)
 				break;
 			mode = native_mode;
 			asyc->scaler.full = true;