layers: Fix get_descriptor_binding
layers: Fix get_descriptor_binding

Not sure where the `return` went... this worked by accidents of calling
conventions in debug, but was rightfully eaten by the optimizer in release.

Signed-off-by: Chris Forbes <c3279c50043e18e9442c1ae071cafa0e7a4ca967@google.com>

KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools