linux-wandboard

mac80211: add debugfs file for current tx rate

Add a debugfs file showing the current tx rate.
The information available in the rc_stats file
doesn't evidently provides us the current tx rate.
This patch adds the support for the same.

Signed-off-by: Saravana <saravanad@posedge.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>