MdeModulePkg PlatformVarCleanupLib: Locate VarCheck protocol when using

Do not locate VarCheck protocol in Constructor, then the
gEdkiiVarCheckProtocolGuid could be removed from [Depex].
It will be more flexible for the library Consumer to work without VarCheck
protocol installed, for example at recovery boot mode with EmuRuntimeDxe.

The unused UefiLib is also been removed from [LibraryClasses] in *.inf.

Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Feng Tian <feng.tian@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>

MdeModulePkg/Library/PlatformVarCleanupLib/PlatformVarCleanupLib.inf

@@ -1,7 +1,7 @@
 ## @file
 #  Sample platform variable cleanup library instance.
 #
-#  Copyright (c) 2015, Intel Corporation. All rights reserved.<BR>
+#  Copyright (c) 2015 - 2016, Intel Corporation. All rights reserved.<BR>
 #
 #  This program and the accompanying materials
 #  are licensed and made available under the terms and conditions
@@ -44,7 +44,6 @@
 [LibraryClasses]
   UefiBootServicesTableLib
   UefiRuntimeServicesTableLib
-  UefiLib
   BaseLib
   DebugLib
   BaseMemoryLib
@@ -68,6 +67,5 @@
   gEfiHiiConfigRoutingProtocolGuid  ## SOMETIMES_CONSUMES
 
 [Depex]
-  gEdkiiVarCheckProtocolGuid AND
   gEfiVariableArchProtocolGuid