staging: wlan-ng: hfa384x.h: fix for error reported by smatch

Add the missing header include for 'struct urb' datatypes to avoid
potential build issues. Found using smatch.

Signed-off-by: Kumar Amit Mehta <gmate.amit@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>