[llvm] [TableGen] Extend OPC_ExtractField/OPC_CheckField start value widths. (PR #79723)

[Jason Eckhardt via llvm-commits]

nvjle wrote:

I hope one of @jyknight @jmolloy @0x59616e (based on recent commits to the same area) might review this small patch, thank you.

https://github.com/llvm/llvm-project/pull/79723