Second:
get the sources for the Driver, from Realtek we use rtl8712_8188_8191_8192SU_usb_linux_v2.6.6.0.20120405.
try sudo ./install.sh, this expand some sources. Goto in the directory driver/rtl...
edit
sudo vim /home/pi/rtl8191su/rtl8712_8188_8191_8192SU_usb_linux_v2.6.6.0.20120405/driver/rtl8712_8188_8191_8192SU_usb_linux_v2.6.6.0.20120405/include/rtl871x_cmd.h
insert the header
#include <linux/interrupt.h>
in the sources, (tipp come from: archlinuxarm form)
make clean, make, make install as root.
Third:
load module at startup - maybee better from udev usb??
append 8712u to /etc/modules
Reboot, that is.
check iw wlan0 list