iwlwifi: mvm: rs: avoid ss_force from being reset after tx idle

ss_force is a debugging option to force a certain single stream
tx mode. It's not useful if it gets reset after tx idle. Fix that.
While at it also make sure any code touching ss_force will only
get compiled if debugfs support is configured.

Signed-off-by: Eyal Shapira <eyalx.shapira@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/mvm/rs.h b/drivers/net/wireless/iwlwifi/mvm/rs.h
index 4cb278f..e4aa934 100644
--- a/drivers/net/wireless/iwlwifi/mvm/rs.h
+++ b/drivers/net/wireless/iwlwifi/mvm/rs.h
@@ -332,14 +332,14 @@
 	/* tx power reduce for this sta */
 	int tpc_reduce;
 
-	/* force STBC/BFER/SISO for testing */
-	enum rs_ss_force_opt ss_force;
-
 	/* persistent fields - initialized only once - keep last! */
 	struct lq_sta_pers {
 #ifdef CONFIG_MAC80211_DEBUGFS
 		u32 dbg_fixed_rate;
 		u8 dbg_fixed_txp_reduction;
+
+		/* force STBC/BFER/SISO for testing */
+		enum rs_ss_force_opt ss_force;
 #endif
 		u8 chains;
 		s8 chain_signal[IEEE80211_MAX_CHAINS];