[llvm] [utils] Add spirv triple to update_llc_test_checks (PR #150223)

[Nathan Gauër via llvm-commits]

Keenuts wrote:

> LGTM - are there many SPIRV uses of the update scripts yet? I didn't noticed anything in CodeGen/SPIRV

Not yet, but I used it for an upcoming PR: https://github.com/llvm/llvm-project/pull/150224

https://github.com/llvm/llvm-project/pull/150223