Fix option desc in FunctionAttrs; NFC

Summary: The example in desc should match with actual option name

Reviewers: jmolloy

Differential Revision: http://reviews.llvm.org/D15800

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256951 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed