iwlwifi: make config const

Writing to the global config structures
is always wrong. To protect against such
mistakes in the future, mark them const.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-shared.h b/drivers/net/wireless/iwlwifi/iwl-shared.h
index 11184f1..4efc9e1 100644
--- a/drivers/net/wireless/iwlwifi/iwl-shared.h
+++ b/drivers/net/wireless/iwlwifi/iwl-shared.h
@@ -374,7 +374,7 @@
 	bool wowlan;
 	u8 valid_contexts;
 
-	struct iwl_cfg *cfg;
+	const struct iwl_cfg *cfg;
 	struct iwl_priv *priv;
 	struct iwl_trans *trans;
 	struct iwl_nic *nic;