wifi: cfg80211: allow IR in 20 MHz configurations

[ Upstream commit cf4bd1608882792d4742e27a819493312904a680 ]

Some regulatory bodies doesn't allow IR (initiate radioation) on a
specific subband, but allows it for channels with a bandwidth of 20 MHz.
Add a channel flag that indicates that, and consider it in
cfg80211_reg_check_beaconing.

While on it, fix the kernel doc of enum nl80211_reg_rule_flags and
change it to use BIT().

Signed-off-by: Anjaneyulu <pagadala.yesu.anjaneyulu@intel.com>
Co-developed-by: Somashekhar Puttagangaiah <somashekhar.puttagangaiah@intel.com>
Signed-off-by: Somashekhar Puttagangaiah <somashekhar.puttagangaiah@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20250308225541.d3ab352a73ff.I8a8f79e1c9eb74936929463960ee2a324712fe51@changeid
[fix typo]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

include/net/cfg80211.h

@@ -127,6 +127,8 @@ struct wiphy;
  *	even if it is otherwise disabled.
  * @IEEE80211_CHAN_ALLOW_6GHZ_VLP_AP: Allow using this channel for AP operation
  *	with very low power (VLP), even if otherwise set to NO_IR.
+ * @IEEE80211_CHAN_ALLOW_20MHZ_ACTIVITY: Allow activity on a 20 MHz channel,
+ *	even if otherwise set to NO_IR.
  */
 enum ieee80211_channel_flags {
 	IEEE80211_CHAN_DISABLED			= BIT(0),
@@ -155,6 +157,7 @@ enum ieee80211_channel_flags {
 	IEEE80211_CHAN_NO_6GHZ_AFC_CLIENT	= BIT(23),
 	IEEE80211_CHAN_CAN_MONITOR		= BIT(24),
 	IEEE80211_CHAN_ALLOW_6GHZ_VLP_AP	= BIT(25),
+	IEEE80211_CHAN_ALLOW_20MHZ_ACTIVITY     = BIT(26),
 };
 
 #define IEEE80211_CHAN_NO_HT40 \