MdePkg UefiLib: Make the event empty function public

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=298

Then this event empty function can be used to remove
the duplication in drivers and other libraries.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

MdePkg/Library/UefiLib/UefiLib.c

@@ -5,7 +5,7 @@
   EFI Driver Model related protocols, manage Unicode string tables for UEFI Drivers, 
   and print messages on the console output and standard error devices.
 
-  Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
   which accompanies this distribution.  The full text of the license may be found at
@@ -332,7 +332,7 @@ EfiEventGroupSignal (
   Status = gBS->CreateEventEx (
                   EVT_NOTIFY_SIGNAL,
                   TPL_CALLBACK,
-                  InternalEmptyFunction,
+                  EfiEventEmptyFunction,
                   NULL,
                   EventGroup,
                   &Event
@@ -347,6 +347,24 @@ EfiEventGroupSignal (
   return Status;
 }
 
+/**
+  An empty function that can be used as NotifyFunction parameter of
+  CreateEvent() or CreateEventEx().
+
+  @param Event              Event whose notification function is being invoked.
+  @param Context            The pointer to the notification function's context,
+                            which is implementation-dependent.
+
+**/
+VOID
+EFIAPI
+EfiEventEmptyFunction (
+  IN EFI_EVENT              Event,
+  IN VOID                   *Context
+  )
+{
+}
+
 /** 
   Returns the current TPL.
 
@@ -1587,23 +1605,3 @@ GetBestLanguage (
   //
   return NULL;
 }
-
-/**
-  An empty function to pass error checking of CreateEventEx ().
-
-  This empty function ensures that EVT_NOTIFY_SIGNAL_ALL is error
-  checked correctly since it is now mapped into CreateEventEx() in UEFI 2.0.
-
-  @param  Event                 Event whose notification function is being invoked.
-  @param  Context               The pointer to the notification function's context,
-                                which is implementation-dependent.
-
-**/
-VOID
-EFIAPI
-InternalEmptyFunction (
-  IN EFI_EVENT                Event,
-  IN VOID                     *Context
-  )
-{
-}