drm/sti: use valid video mode

In atomic mode the crtc_xxx (eg crtc_hdisplay) members of the mode
structure may be unset before calling atomic_check/commit for planes.
Instead of, use xxx members which are actually set.

Signed-off-by: Fabien Dessenne <fabien.dessenne@st.com>
Acked-by: Vincent Abriou <vincent.abriou@st.com>

drivers/gpu/drm/sti/sti_vid.c

@@ -142,8 +142,8 @@ void sti_vid_commit(struct sti_vid *vid,
 	struct drm_display_mode *mode = &crtc->mode;
 	int dst_x = state->crtc_x;
 	int dst_y = state->crtc_y;
-	int dst_w = clamp_val(state->crtc_w, 0, mode->crtc_hdisplay - dst_x);
-	int dst_h = clamp_val(state->crtc_h, 0, mode->crtc_vdisplay - dst_y);
+	int dst_w = clamp_val(state->crtc_w, 0, mode->hdisplay - dst_x);
+	int dst_h = clamp_val(state->crtc_h, 0, mode->vdisplay - dst_y);
 	int src_h = state->src_h >> 16;
 	u32 val, ydo, xdo, yds, xds;