wifi: cfg80211: fix cfg80211 function kernel-doc

Running "scripts/kernel-doc -Wall -Werror -none include/net/cfg80211.h"
produces many warnings of the form "warning: No description found for
return value of <function>", so make sure all of them have a Return:
clause. In some instances also add a Context: clause.
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Link: https://msgid.link/20240417-cfg80211-kdoc-v1-1-d54cb7143417@quicinc.comSigned-off-by: Johannes Berg <johannes.berg@intel.com>