Remove redundant void from error messages

It's not neeeded.

Tested:
Code compiles.  No functional changes.

Signed-off-by: Ed Tanous <ed@tanous.net>
Change-Id: I21588b8ca2bab4ddb65d9c6d910ba26db83c323b
diff --git a/redfish-core/include/resource_messages.hpp b/redfish-core/include/resource_messages.hpp
index 17157fe..95ace94 100644
--- a/redfish-core/include/resource_messages.hpp
+++ b/redfish-core/include/resource_messages.hpp
@@ -5,7 +5,7 @@
 namespace messages
 {
 
-inline nlohmann::json resourceChanged(void)
+inline nlohmann::json resourceChanged()
 {
     return nlohmann::json{
         {"EventType", "ResourceChanged"},
@@ -16,7 +16,7 @@
         {"MessageSeverity", "OK"}};
 }
 
-inline nlohmann::json resourceCreated(void)
+inline nlohmann::json resourceCreated()
 {
     return nlohmann::json{
         {"EventType", "ResourceAdded"},
@@ -27,7 +27,7 @@
         {"MessageSeverity", "OK"}};
 }
 
-inline nlohmann::json resourceRemoved(void)
+inline nlohmann::json resourceRemoved()
 {
     return nlohmann::json{
         {"EventType", "ResourceRemoved"},