Fix DeviceInfo objects comparing
Fix DeviceInfo objects comparing

Do not crash if the other object is completely different type. Return
False ("unequal") instead.

This crashed preparing list of devices in qubes-vm-boot-from-device.

Fixes QubesOS/qubes-issues#3182

marmarek/qubes-core-mgmt-client,marmarek/qubes-core-mgmt-client,marmarek/qubes-core-mgmt-client