ath5k: ath5k_setup_channels cleanup and whitespace

Remove useless test_bit - it's not going to happen because of the way this
function is called only when that bit is set.

And fix some whitespace.

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