vulkan/overlay: fix truncating error on 32bit platforms

Non dispatchable handles can be uint64_t. When compiling the layer on
a 32bit platform, this will lead to casting uint64_t into (void *)
which is 32bit, leading to incorrect handles being mapped internally
in the layer.

v2: Use more HKEY() (Eric)

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reported-by: Józef Kucia <joseph.kucia@gmail.com>
Fixes: 2d292793 ("vulkan/overlay-layer: fix cast errors")
Reviewed-by: Józef Kucia <joseph.kucia@gmail.com>
(cherry picked from commit 877b371c)
[Juan: resolve trivial conflicts]
Signed-off-by: Juan A. Suarez Romero <jasuarez@igalia.com>

Conflicts:
	src/vulkan/overlay-layer/overlay.cpp