[U-Boot] [PATCH v3 21/31] virtio: Add virtio over pci transport driver

[sjg at google.com]

This adds a transport driver that implements UCLASS_VIRTIO for
virtio over pci, which is commonly used on x86.

It only supports the legacy interface of the pci transport, which
is the default device that QEMU emulates.

Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
Reviewed-by: Simon Glass <sjg at chromium.org>
---

Changes in v3: None
Changes in v2: None

 drivers/virtio/Kconfig      |   8 +
 drivers/virtio/Makefile     |   1 +
 drivers/virtio/virtio_pci.c | 421 ++++++++++++++++++++++++++++++++++++++++++++
 drivers/virtio/virtio_pci.h | 173 ++++++++++++++++++
 4 files changed, 603 insertions(+)
 create mode 100644 drivers/virtio/virtio_pci.c
 create mode 100644 drivers/virtio/virtio_pci.h

Applied to u-boot-dm/next, thanks!