ath9k: Print rxfilter in debugfs.

Print raw and decoded rxfilter in debufs 'wiphy' file.

Also, move variable-length printouts to bottom of file to
make bounds checking easier.

Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>