[clang] [Sema] Fixed faulty shift count warning (PR #69521)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> Alright, looks like @shafik isn't going to review this, so I'll just have to accept it. LGTM.

FWIW, he was out of town all last week and a bit of the week before that. I think he's still digging out from under the mountain of email.

Changes LGTM as well!

https://github.com/llvm/llvm-project/pull/69521