radv: correctly use vulkan 1.0 by default

From the vulkan spec 3.2 "Instances":

"Providing a NULL VkInstanceCreateInfo::pApplicationInfo or providing an
apiVersion of 0 is equivalent to providing an apiVersion of
VK_MAKE_VERSION(1,0,0)."

Fixes: ffa15861 "radv: UseEnumerateInstanceVersion for the default version."
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
(cherry picked from commit d12dc393)