Revert part of r321026 "[X86] Don't use NOPL when the assembler is pa…

…ssed an empty CPU string." while I investigate how to fix an lld test failure.

Looks like lld also needs to pass a -mcpu in some of its tests

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@321033 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp

@@ -78,7 +78,7 @@ class X86AsmBackend : public MCAsmBackend {
               CPU != "i586" && CPU != "pentium" && CPU != "pentium-mmx" &&
               CPU != "i686" && CPU != "k6" && CPU != "k6-2" && CPU != "k6-3" &&
               CPU != "geode" && CPU != "winchip-c6" && CPU != "winchip2" &&
-              CPU != "c3" && CPU != "c3-2" && CPU != "lakemont" && CPU != "";
+              CPU != "c3" && CPU != "c3-2" && CPU != "lakemont";
   }
 
   unsigned getNumFixupKinds() const override {