[llvm] [CodeGenTypes] Remove explicit VT numbers from ValueTypes.td (PR #169670)

[Craig Topper via llvm-commits]

topperc wrote:

> @s-barannikov pointed out an alternative patch from just a few days ago: #169071

I think I prefer this patch over using `instances`. But let's see what other reviewers think.

https://github.com/llvm/llvm-project/pull/169670