AMDGPU: Fix adding m0 uses to gfx12 ds atomics
The DS multiclasses are poorly named. The base forms
include the legacy pseudo with the m0 implicit use, plus
a _gfx9 suffixed version without. The _gfx9 multiclass
only defines an unsuffixed version without m0, so use tha
one.
Fixes unnecessarily depending on m0 for ds_cond_sub_rtn_u32.
