virtio: pci: Allow exclusion of legacy driver

Add a new config to control whether the driver for legacy virtio PCI
devices is included in the build. VIRTIO_PCI_LEGACY is included by
default when VIRTIO_PCI is selected, but it can also be independently
toggled.

Signed-off-by: Andrew Scull <ascull@google.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
2 files changed