ath9k: Merge wiphy and misc debugfs files

This patch merges the 'wiphy' and 'misc' debugfs files
and consolidates the information.

Information about the current channel and other HT parameters
can be obtained from both mac80211 and iw. Remove such
redundant data.

The reset statistics have been removed, they will be re-added in
a subsequent patch (in a new debugfs file).

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>