vulkan/overlay: fix timestamp query emission with no pipeline stats

The
   if (!pipe && timestamp)

logic was broken. It should have been :

   if (!pipe && !timestamp)

Let just drop this condition as the following code does the right
thing for all cases.

An error was appearing with the following variables :

VK_INSTANCE_LAYERS=VK_LAYER_MESA_overlay VK_LAYER_MESA_OVERLAY_CONFIG=gpu_timing

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Fixes: ea7a6fa9 ("vulkan/overlay: add pipeline statistic & timestamps support")
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
(cherry picked from commit 213d6527)