staging: vt6656: iwctl_giwaplist/device_ioctl : use off stack buffers.
Calls ioctl SIOCGIWAPLIST use off stack buffers.
clears up warning messages.
main_usb.c:2015:1: warning: the frame size of 1888 bytes is larger than 1024 bytes [-Wframe-larger-than=]
iwctl.c:683:1: warning: the frame size of 1280 bytes is larger than 1024 bytes [-Wframe-larger-than=]