ac/llvm: vs_rel_patch_id can also be fixed up

It's currently used when LS store output to LDS.
The LS/HS bug fix seems does not affect this case.
But we'd better treat it as other fixed args.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Signed-off-by: Qiang Yu <yuq825@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22045>

src/amd/llvm/ac_shader_abi.h

@@ -44,6 +44,7 @@ struct ac_shader_abi {
 
    /* These input registers sometimes need to be fixed up. */
    LLVMValueRef vertex_id;
+   LLVMValueRef vs_rel_patch_id;
    LLVMValueRef instance_id;
    LLVMValueRef persp_centroid, linear_centroid;
    LLVMValueRef color0, color1;