[llvm] [AMDGPU] Enable XNACK on gfx1250 (PR #161457)

[Shilei Tian via llvm-commits]

shiltian wrote:

@rampitec It looks like this doesn't work well with the test case `llvm/test/tools/llvm-objdump/ELF/AMDGPU/kd-gfx1250.s`, regarding `.amdhsa_reserve_xnack_mask 0`. Based on `llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp:2279`, it always uses `.amdhsa_reserve_xnack_mask 0`, but this will lead to unmatched feature. Do you have any suggestions?

https://github.com/llvm/llvm-project/pull/161457