drm/ast: drop duplicate initialization

We set ".disable" to "ast_crtc_disable" twice.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/ast/ast_mode.c

@@ -582,7 +582,6 @@ static const struct drm_crtc_helper_funcs ast_crtc_helper_funcs = {
 	.mode_set_base = ast_crtc_mode_set_base,
 	.disable = ast_crtc_disable,
 	.load_lut = ast_crtc_load_lut,
-	.disable = ast_crtc_disable,
 	.prepare = ast_crtc_prepare,
 	.commit = ast_crtc_commit,