I used the flashable package from Tun4f1sh. Anyway I solved like this.
1) restored nandroid backup made before update
2) extracted bcm4329.ko file from system/lib/modules subdirectory on the phone and copied on sdcard
3) flashed again the update
4) restarted phone and copied the original bcm4329.ko file to system/lib/modules subdirectory overwriting the existing new one with EsFileExplorer in root mode.
5) restart phone
All right, now the phone is updated to last version and the wifi driver is correct and functioning ;)