staging: rtl8723au: rtl8723a_cmd.c: Use ieee80211.h provided fctl bits

v2: Fix endian bug reported by Dan Carpenter <dan.carpenter@oracle.com>

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>