package/x11r7/xdriver_xf86-video-r128: don't override XDRIVER_XF86_VIDEO_R128_CONF_OPTS

XDRIVER_XF86_VIDEO_R128_CONF_OPTS is wrongly overridden in a conditional
since commit 082b65319c90ea5c9a89ff4ffed12af3a3e952b6

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/x11r7/xdriver_xf86-video-r128/xdriver_xf86-video-r128.mk

@@ -12,7 +12,7 @@ XDRIVER_XF86_VIDEO_R128_LICENSE_FILES = COPYING
 XDRIVER_XF86_VIDEO_R128_DEPENDENCIES = xserver_xorg-server xorgproto
 
 ifeq ($(BR2_PACKAGE_MESA3D_DRI_DRIVER),)
-XDRIVER_XF86_VIDEO_R128_CONF_OPTS = --disable-dri
+XDRIVER_XF86_VIDEO_R128_CONF_OPTS += --disable-dri
 endif
 
 $(eval $(autotools-package))