iwlwifi: iwl_good_ack_health() only apply to AGN device

iwl_good_ack_health() check for expected and actual ack count which only
apply to aggregation mode. Move the function to iwlagn module.

Reported-by: Chantry Xavier <chantry.xavier@gmail.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn.h b/drivers/net/wireless/iwlwifi/iwl-agn.h
index 26eeb58..42c291b 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn.h
+++ b/drivers/net/wireless/iwlwifi/iwl-agn.h
@@ -70,5 +70,7 @@
 int iwl_alloc_isr_ict(struct iwl_priv *priv);
 void iwl_free_isr_ict(struct iwl_priv *priv);
 irqreturn_t iwl_isr_ict(int irq, void *data);
+bool iwl_good_ack_health(struct iwl_priv *priv,
+			 struct iwl_rx_packet *pkt);
 
 #endif /* __iwl_agn_h__ */