ac/llvm: set the correct cache policy for sparse buffer loads

The DLC bit was missing on gfx10.

Fixes: 6d5e26752c "ac/nir: implement sparse image/texture loads"
Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16215>

src/amd/llvm/ac_llvm_build.c

@@ -1257,6 +1257,8 @@ LLVMValueRef ac_build_buffer_load_format(struct ac_llvm_context *ctx, LLVMValueR
    if (tfe) {
       assert(!d16);
 
+      cache_policy = get_load_cache_policy(ctx, cache_policy);
+
       char code[256];
       /* The definition in the assembly and the one in the constraint string
        * differs because of an assembler bug.