IntelFrameworkPkg 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 D Kinney <michael.d.kinney@intel.com>
Cc: Jeff Fan <jeff.fan@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Jeff Fan <jeff.fan@intel.com>

IntelFrameworkPkg/Library/FrameworkUefiLib/UefiNotTiano.c

@@ -45,7 +45,7 @@ EfiCreateEventLegacyBoot (
 {
   return EfiCreateEventLegacyBootEx (
            TPL_CALLBACK,
-           InternalEmptyFunction,
+           EfiEventEmptyFunction,
            NULL,
            LegacyBootEvent
            );
@@ -135,7 +135,7 @@ EfiCreateEventReadyToBoot (
 {
   return EfiCreateEventReadyToBootEx (
            TPL_CALLBACK,
-           InternalEmptyFunction,
+           EfiEventEmptyFunction,
            NULL,
            ReadyToBootEvent
            );