ShellPkg: Fixed build error 'variable set but not used'

GCC toolchain cannot build ShellPkg.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Harry Liebel <Harry.Liebel@arm.com>
Signed-off-by: Olivier Martin <Olivier.Martin@arm.com>
Reviewed-by: Jaben Carsey <Jaben.Carsey@intel.com>

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@14326 6f19259b-4bc3-4df7-8a09-765794883524

ShellPkg/Library/UefiShellLevel1CommandsLib/If.c

@@ -662,12 +662,9 @@ BuildNextStatement (
   OUT END_TAG_TYPE  *EndTag
   )
 {
-  CHAR16    *Buffer;
-  UINTN     BufferSize;
-
   *EndTag = EndTagMax;
 
-  for(Buffer = NULL, BufferSize = 0
+  for(
     ; ParameterNumber < gEfiShellParametersProtocol->Argc
     ; ParameterNumber++
    ) {