wifi: cfg80211: reg: fix various kernel-doc issues

Clean up the kernel-doc comments in reg.h.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230827135854.36d7b52da0f5.I85fbfb3095613f4a0512493cbbdda881dc31be2c@changeid


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