MdeModulePkg: Remove duplicate library class in dsc file

In MdeModulePkg.dsc, CapsuleLib appears twice in [LibraryClasses]
section, so remove the duplicate one.

Signed-off-by: Qihang Gao <[email protected]>

Author: EricGao2015

MdeModulePkg/MdeModulePkg.dsc

@@ -100,7 +100,6 @@
   ImagePropertiesRecordLib|MdeModulePkg/Library/ImagePropertiesRecordLib/ImagePropertiesRecordLib.inf
 
   FmpAuthenticationLib|MdeModulePkg/Library/FmpAuthenticationLibNull/FmpAuthenticationLibNull.inf
-  CapsuleLib|MdeModulePkg/Library/DxeCapsuleLibNull/DxeCapsuleLibNull.inf
   BmpSupportLib|MdeModulePkg/Library/BaseBmpSupportLib/BaseBmpSupportLib.inf
   SafeIntLib|MdePkg/Library/BaseSafeIntLib/BaseSafeIntLib.inf
   DisplayUpdateProgressLib|MdeModulePkg/Library/DisplayUpdateProgressLibGraphics/DisplayUpdateProgressLibGraphics.inf