kernel-doc: fix new warnings in cfg80211.h

Fix new kernel-doc warnings:

Warning(include/net/cfg80211.h:1165): No description found for parameter 'channel_type'
Warning(include/net/cfg80211.h:2090): No description found for parameter 'probe_resp_offload'

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Cc:	Johannes Berg <johannes@sipsolutions.net>
Cc:	linux-wireless@vger.kernel.org
Signed-off-by: John W. Linville <linville@tuxdriver.com>