v1.20.1
[legal] Relicense files under GPL2_OR_LATER_OR_UBDL
[device] Make driver name a generic device property
[isa] Avoid spurious compiler warning on gcc 4.7
[build] Rename gPXE to iPXE
[legal] Update FSF mailing address in GPL licence texts
[pci] Support systems with multiple PCI root bridges
[pci] Add support for PCI Enhanced Allocation
[pci] Add pci_find_next_capability()
[pci] Add support for PCI MSI-X interrupts
[usb] Use non-zero language ID to retrieve strings
[virtio] Remove queue size limit in legacy virtio
[virtio] Add virtio 1.0 PCI support