Recent upstream trends have moved away from explicitly using `-verify-machineinstrs`, as it's already covered by the expensive checks. This PR removes almost all `-verify-machineinstrs` from tests in `llvm/test/CodeGen/AMDGPU/*.ll`, leaving only those tests where its removal currently causes failures.
Remove DAGISel checks on calling conventions. GlobalISel doesn't have
these checks either and we prefer it that way (see D152794).
Add a simple test like the one introduced in D117479 for GlobalISel.
Differential Revision: https://reviews.llvm.org/D153535