cmd is allocated in pn533_dep_link_up and passed as an arg to
pn533_send_cmd_frame_async together with a complete cb.

arg is passed to the cb and must be kfreed there.
Signed-off-by: NWaldemar Rymarkiewicz <waldemar.rymarkiewicz@tieto.com>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>