brcm2708: drop wpad-mini as it clashes with hostapd-mini (#1205)

targets/brcm2708-bcm2710

@@ -1,3 +1,4 @@
 device raspberry-pi-3 rpi-3
 factory -ext4-sdcard .img.gz
 sysupgrade -ext4-sdcard .img.gz
+packages '-wpad-mini' # clashes with hostapd-mini