[AMDGPU] Add a trap lowering workaround for gfx11 (#85854)

On gfx11 shaders run with PRIV=1, which causes `s_trap 2` to be treated
as a nop, which means it isn't a correct lowering for the trap
intrinsic. As a workaround, this commit instead lowers the trap
intrinsic to instructions that simulate the behavior of s_trap 2.

Fixes: SWDEV-438421