staging: wlan-ng: Use kzalloc instead of kmalloc.

This patch uses kzalloc instead of kmalloc function.
A coccinelle script was used to make this change.

Signed-off-by: Navya Sri Nizamkari <navyasri.tech@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>