nak/nir: Use Kepler texture source ordering on SM30

SM30 (i.e. Kepler A) has Fermi's instruction encoding but it uses the
same texture source ordering as Kepler B.  It also supports bindless,
unlike Fermi.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34540>

src/nouveau/compiler/nak_nir_lower_tex.c

@@ -237,7 +237,7 @@ lower_tex(nir_builder *b, nir_tex_instr *tex, const struct nak_compiler *nak)
          tex->src[1].src_type = nir_tex_src_backend2;
          nir_src_rewrite(&tex->src[1].src, nir_vec(b, src1, src1_comps));
       }
-   } else if (nak->sm >= 32) {
+   } else if (nak->sm >= 30) {
       nir_def *src[8] = { NULL, };
       unsigned src_comps = 0;