[AMD] Disable True16 for assembler on gfx11 (triton-lang#9447)

We already disable True16 on gfx11 in make_amdgcn, but since a recent
LLVM bump the assembler rejects Fake16 instructions by default,
requiring us to disable True16 here as well.

Co-authored-by: Paul Trojahn <paul.trojahn@amd.com>

Author: ptrojahn

third_party/amd/backend/compiler.py

@@ -490,6 +490,8 @@ def make_hsaco(src, metadata, options):
         target_features = ''
         if knobs.compilation.enable_asan:
             target_features = '+xnack'
+        if 'gfx11' in options.arch:
+            target_features += ',-real-true16'
         hsaco = amd.assemble_amdgcn(src, options.arch, target_features)
         with tempfile.NamedTemporaryFile() as tmp_out:
             with tempfile.NamedTemporaryFile() as tmp_in: