iwlwifi: mvm: fix NVM parsing error path

If NVM parsing fails and returns NULL, we continue in
the code flow and eventually crash accessing the NULL
pointer. Return an error from iwl_nvm_init() if the
parsing failed.
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/iwlwifi/mvm/nvm.c

@@ -231,8 +231,9 @@ int iwl_nvm_init(struct iwl_mvm *mvm)
 	if (ret < 0)
 		return ret;
 
-	ret = 0;
 	mvm->nvm_data = iwl_parse_nvm_sections(mvm);
+	if (!mvm->nvm_data)
+		return -ENODATA;
 
-	return ret;
+	return 0;
 }