Some drivers were in the kernel, but later they were removed and later on again put there. What was working with older kernel don't mean that it will work now. Check the kernel module directory if the driver is there. If no, try to install firmware-realtek. Than replug the dongle.
Use
lsmod
and look if the module is there, mostly at the top. If no, than the issue is still in the driver.
If yes, than try:
iwconfig
There may appear wlan0. If it is there, than everything will work fine.