iwlwifi: mvm: update values for Smart Fifo

Interoperability issues were identified and root caused to
the Smart Fifo watermarks. These issues arose with
NetGear R7000. Fix this.

Cc: <stable@vger.kernel.org> [3.14+]
Fixes: 1f3b0ff8 ("iwlwifi: mvm: Add Smart FIFO support")
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

drivers/net/wireless/iwlwifi/mvm/fw-api.h

@@ -1615,7 +1615,7 @@ enum iwl_sf_scenario {
 #define SF_NUM_TIMEOUT_TYPES 2		/* Aging timer and Idle timer */
 
 /* smart FIFO default values */
-#define SF_W_MARK_SISO 4096
+#define SF_W_MARK_SISO 6144
 #define SF_W_MARK_MIMO2 8192
 #define SF_W_MARK_MIMO3 6144
 #define SF_W_MARK_LEGACY 4096