[clang] [clang] Avoid warnings about enum mismatch in ternary expressions. NFC. (PR #159338)

[Bruno De Fraine via cfe-commits]

brunodf-snps wrote:

@mstorsjo It seems you are (by coincidence) looking into warnings of a gcc build at the same time as I was. There was a third PR about a gcc warning: #158635

https://github.com/llvm/llvm-project/pull/159338