agx: Re-index nir defs to reduce memory usage

nir_index_ssa_defs(..) will re-index the function impl and will
update ssa_alloc. In almost all cases this will result in a lower
ctx->alloc number which reduces memory usage in compiler passes
that are using ctx-alloc to allocate memory.

Signed-off-by: Christian Gmeiner <cgmeiner@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26056>

src/asahi/compiler/agx_compile.c

@@ -2619,6 +2619,7 @@ agx_compile_function_nir(nir_shader *nir, nir_function_impl *impl,
                          struct agx_shader_info *out)
 {
    nir_index_blocks(impl);
+   nir_index_ssa_defs(impl);
 
    agx_context *ctx = rzalloc(NULL, agx_context);
    ctx->nir = nir;