wifi: cfg80211: add return docs for regulatory functions

Add return value documentation for regulatory functions
that are missing it.

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

net/wireless/reg.h

@@ -137,13 +137,14 @@ void regulatory_hint_disconnect(void);
  * Get a value specifying the U-NII band frequency belongs to.
  * U-NII bands are defined by the FCC in C.F.R 47 part 15.
  *
- * Returns -EINVAL if freq is invalid, 0 for UNII-1, 1 for UNII-2A,
+ * Return: -EINVAL if freq is invalid, 0 for UNII-1, 1 for UNII-2A,
  * 2 for UNII-2B, 3 for UNII-2C and 4 for UNII-3.
  */
 int cfg80211_get_unii(int freq);
 
 /**
  * regulatory_indoor_allowed - is indoor operation allowed
+ * Return: %true if indoor operation is allowed, %false otherwise
  */
 bool regulatory_indoor_allowed(void);
 
@@ -173,11 +174,13 @@ void regulatory_propagate_dfs_state(struct wiphy *wiphy,
  * reg_dfs_domain_same - Checks if both wiphy have same DFS domain configured
  * @wiphy1: wiphy it's dfs_region to be checked against that of wiphy2
  * @wiphy2: wiphy it's dfs_region to be checked against that of wiphy1
+ * Return: %true if both wiphys have the same DFS domain, %false otherwise
  */
 bool reg_dfs_domain_same(struct wiphy *wiphy1, struct wiphy *wiphy2);
 
 /**
  * reg_reload_regdb - reload the regulatory.db firmware file
+ * Return: 0 for success, an error code otherwise
  */
 int reg_reload_regdb(void);