ath10k: detect the number of spatial streams supported by hw

Until now ath10k assumed 3 spatial streams.
However some devices support only 2 spatial
streams.

This patch improves performance on devices that
don't support 3 spatial streams.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
diff --git a/drivers/net/wireless/ath/ath10k/core.h b/drivers/net/wireless/ath/ath10k/core.h
index 9f21ecb..ff42bb7 100644
--- a/drivers/net/wireless/ath/ath10k/core.h
+++ b/drivers/net/wireless/ath/ath10k/core.h
@@ -285,6 +285,7 @@
 	u32 hw_max_tx_power;
 	u32 ht_cap_info;
 	u32 vht_cap_info;
+	u32 num_rf_chains;
 
 	struct targetdef *targetdef;
 	struct hostdef *hostdef;