nir: fix deref offset builder

Use the correct bit size

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

src/compiler/nir/nir_deref.c

@@ -292,7 +292,7 @@ nir_build_deref_offset(nir_builder *b, nir_deref_instr *deref,
 
    assert(path.path[0]->deref_type == nir_deref_type_var);
 
-   nir_ssa_def *offset = nir_imm_int(b, 0);
+   nir_ssa_def *offset = nir_imm_intN_t(b, 0, deref->dest.ssa.bit_size);
    for (nir_deref_instr **p = &path.path[1]; *p; p++) {
       if ((*p)->deref_type == nir_deref_type_array) {
          nir_ssa_def *index = nir_ssa_for_src(b, (*p)->arr.index, 1);