[X86] Remove unused IES_IDENTIFIER state from IntelExprState. NFC

Author: topperc

llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp

@@ -422,7 +422,6 @@ class X86AsmParser : public MCTargetAsmParser {
     IES_RPAREN,
     IES_REGISTER,
     IES_INTEGER,
-    IES_IDENTIFIER,
     IES_ERROR
   };