anv: Don't teardown uninitialized anv_physical_device
anv: Don't teardown uninitialized anv_physical_device

If the user called vkDestroyDevice but never called
vkEnumeratePhysicalDevices, then the driver tried to ralloc_free() an
unitialized anv_physical_device.

Fixes test 'dEQP-VK.api.device_init.create_instance_name_version'.

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler