src/device/pci: Add support for discrete VGA initialization and OpROM loading

Required to make the discrete VGA working at some boards like AMD Lenovo G505S.

If CONFIG_MULTIPLE_VGA_ADAPTERS is enabled: coreboot will try to initialize the
discrete VGA of PCI_CLASS_DISPLAY_OTHER class and load OpROM on it. ACPI VFCT
table will be created only for discrete VGA of PCI_CLASS_DISPLAY_OTHER class
instead of integrated (to avoid the discrete VGA init problems), but everything
is working fine. Later will try to make a common VFCT table for both adapters.

Based on the original patches by Hans Jürgen Kitter <eforname@freemail.hu>.

Signed-off-by: Mike Banon <mikebdp2@gmail.com>
Signed-off-by: Hans Jürgen Kitter <eforname@freemail.hu>
Change-Id: If3269a0911e86ea07014484365c7c830485e52ec
---
M src/device/pci_device.c
M src/device/pci_rom.c
2 files changed, 75 insertions(+), 11 deletions(-)