ath5k: remove debug_dump_skb() functions

Now that rx and tx dumps go through the tracing infrastructure,
we no longer need to keep these routines around.

Signed-off-by: Bob Copeland <me@bobcopeland.com>
Acked-by: Bruno Randolf <br1@einfach.org>
Acked-by: Nick Kossifidis <mickflemm@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>