UefiPayloadPkg: Scan for Option ROMs

Since on UefiPayload the full PCI enumeration isn't run, the light
enumeration won't find Option ROMs. The introduced PciPlatform
driver relies on completed PCI enumeration and assumes that all
ROM bars have been properly assigned a free MMIO window.

Installs the gPciPlatformProtocol to scan for Option ROMs during
PCI enumeration light and copies found Option ROMs to runtime allocated
buffers. Only for work devices that have a ROMBAR, but doesn't for
devices that need a VBIOS loaded from SPI flash.

TEST: QEMU can enumerate Option ROMs on VGA and NIC on UefiPayloadPkg.

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>

Author: PatrickRudolph