staging: rtl8723au: tid is 4 bits, so we need a 16 bit value to hold a bitmap

Remove unused add_enable_bitmap and candidate_tid_bitmap from struct
mlme_ext_info.

In addition we don't need to use CHKBIT when we know we are dealing
with a value in the range 0-15.

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