realtek: drop source-only from rtl931x target
Now the rtl931x target has real devices that need to be built. Remove the
source-only flag to make the images available.
Signed-off-by: Sven Eckelmann <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/20172
Signed-off-by: Hauke Mehrtens <[email protected]>