[coreboot] [PATCH]Move MCP55 PCIe config from romstage to Kconfig

[Patrick Georgi]

Hi,

attached patch is another step towards getting rid of configuration in
romstage.cs.

Move MCP55_PCI_E_X_* to Kconfig. Any useless values in romstage.cs were
not brought over to Kconfig (this applies to all #defines to 4, as
that's the default anyway)

Signed-off-by: Patrick Georgi