iwlagn: store the irq number to iwl_bus just like dev

Since the irq number is just an unsigned int, store it inside iwl_bus
instead of calling the get_irq ops every time it is needed.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-dev.h b/drivers/net/wireless/iwlwifi/iwl-dev.h
index 2d13d89..8ec04f2 100644
--- a/drivers/net/wireless/iwlwifi/iwl-dev.h
+++ b/drivers/net/wireless/iwlwifi/iwl-dev.h
@@ -1224,6 +1224,7 @@
 	struct iwl_priv *priv; /* driver's context */
 	struct device *dev;
 	struct iwl_bus_ops *ops;
+	unsigned int irq;
 };
 
 struct iwl_priv {