vkgears: do not require vulkan 1.1
We're passing zero as the flags to vkGetDeviceQueue2, meaning we might as well use vkGetDeviceQueue from Vulkan 1.0 instead. And this seems to be the only reason we depended on Vulkan 1.1 to start with.
This makes it easier to use vkgears to test early bootstrapped Vulkan implementations.