staging/wlan-ng: use kzalloc rather using kmalloc at create_wlan

instead we would have used kzalloc, so our memory which is allocated will be set to 0.

codepath:

the code path here is prism2sta_probe_usb, calling when ever usb-dev id
and usb-vendor id e.t.c matches with what ever present in the MODULE_DEVICE_TABLE,

and in prism2sta_probe_usb , we call create_wlan, and its called nowhere else...

Signed-off-by: Devendra Naga <devendra.aaru@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>