libvulkan: fix support for 1.1 vkEnumeratePhysicalDeviceGroups

When the icd instance is 1.0, VK_KHR_device_group_creation will be
enabled by the loader if the extension is advertised. Then we will try
to use vkEnumeratePhysicalDeviceGroupsKHR as a fallback.

Bug: 160276146
Test: adb shell cmd gpu vkjson
Test: dEQP-VK.api.info.instance.physical_device_groups
Change-Id: I9e2d9af66e80244f1d43b54ac2800316200c0d00