drm/i915/overlay: Prevent divide by zero bugs in scaling

Smatch detected a divide by zero bug in check_overlay_scaling().

    drivers/gpu/drm/i915/display/intel_overlay.c:976 check_overlay_scaling()
    error: potential divide by zero bug '/ rec->dst_height'.
    drivers/gpu/drm/i915/display/intel_overlay.c:980 check_overlay_scaling()
    error: potential divide by zero bug '/ rec->dst_width'.

Prevent this by ensuring that the dst height and width are non-zero.

Fixes: 02e792f ("drm/i915: implement drmmode overlay support v4")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220124122409.GA31673@kili

drivers/gpu/drm/i915/display/intel_overlay.c

@@ -960,6 +960,9 @@ static int check_overlay_dst(struct intel_overlay *overlay,
 	const struct intel_crtc_state *pipe_config =
 		overlay->crtc->config;
 
+	if (rec->dst_height == 0 || rec->dst_width == 0)
+		return -EINVAL;
+
 	if (rec->dst_x < pipe_config->pipe_src_w &&
 	    rec->dst_x + rec->dst_width <= pipe_config->pipe_src_w &&
 	    rec->dst_y < pipe_config->pipe_src_h &&