[llvm] [AMDGPU] Make s_setprio_inc_wg a scheduling boundary (PR #154188)

[Stanislav Mekhanoshin via llvm-commits]

rampitec wrote:

> no test?

That one is hard to test like most of the scheduling, but basically an user of it wants to have a portion of the code to execute with a different priority, so we do not want to mix the code into that portion. That is similar to the s_setprio instruction just above.

https://github.com/llvm/llvm-project/pull/154188