pan/va: fix bi_is_imm_desc_handle early return

In the bi_emit_load_attr call site, we can use the imm_index value even
if the function returns false. The bifrost path handles this correctly.

Fixes: 652e1c2e13 ("pan/bi: Rework indices for attributes on Valhall")
Signed-off-by: Olivia Lee <olivia.lee@collabora.com>
Reviewed-by: Mary Guillemard <mary.guillemard@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37464>

src/panfrost/compiler/bifrost_compile.c

@@ -458,10 +458,11 @@ bi_is_imm_desc_handle(bi_builder *b, nir_intrinsic_instr *instr,
       uint32_t table_index = pan_res_handle_get_table(res_handle);
       uint32_t res_index = pan_res_handle_get_index(res_handle);
 
+      *immediate = res_handle;
+
       if (!va_is_valid_const_table(table_index) || res_index >= max)
          return false;
 
-      *immediate = res_handle;
       return true;
    }