Fix a clang-tidy warning in VisitVarHandleGetAndAdd()

Fixes a commented argument name mismatch in
IntrinsicCodeGeneratorX86::VisitVarHandleGetAndAdd().

Bug: 168883594
Test: WITH_TIDY=1 m
Change-Id: I526dbe05610301d34457a735dee5fe162ab3230a
1 file changed