drm/nv50: fill in crtc mode struct members from crtc_mode_fixup

The DRM uses the adjusted mode to calculate constants for vblank
timestamping.  Our encoder mode_fixup (usually) replaces this data
with our backend mode information, which doesn't have the needed
data filled in already.

Reported-by: Mario Kleiner mario.kleiner.de@gmail.com
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nv50_display.c

@@ -1035,6 +1035,7 @@ static bool
 nv50_crtc_mode_fixup(struct drm_crtc *crtc, const struct drm_display_mode *mode,
 		     struct drm_display_mode *adjusted_mode)
 {
+	drm_mode_set_crtcinfo(adjusted_mode, CRTC_INTERLACE_HALVE_V);
 	return true;
 }