It's now possible to have a different vGPU type for each pGPU. By modifying
the config, you can say which PCI device (ie. a pGPU) should use a specific
vGPU type.
For upgrades, the behaviour from Train won't be changed since we only use
the first type if we don't have the dynamic options (so operators don't
need to change nova.conf before upgrading).
Implements: blueprint vgpu-multiple-types
Change-Id: I46f0a76811142888db2bbc66cc3fde04ff890c01
5b5cbc64f9