device: EmulatedDevice::services should access the VM config

[dlrobertson]

The EmulatedDevice::services method should be able to access the VirtualMachineConfig. This is not necessary now, but after https://github.com/mythril-hypervisor/mythril/pull/76 we should get the Interrupt Control Address from the VirtualMachineConfig.

[maelgui]

I'll try to address this issue