ath: make gcc check format arguments of ath_print(), fix all misuses

ath: make gcc check format arguments of ath_print(), fix all misuses

Numeric channel is hard to get, so it won't be printed.  Replace Mhz
with MHz on the affected lines and add commas as needed.

Signed-off-by: Pavel Roskin <proski@gnu.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>