This patch adds support for dynamic configuration of PCIe ports for the
AMCC PPC4xx boards equipped with PCIe interfaces. These are the PPC440SPe
boards Yucca & Katmai and the 405EX board Kilauea.

This dynamic configuration is done via the "pcie_mode" environement
variable. This variable can be set to "EP" or "RP" for endpoint or
rootpoint mode. Multiple values can be joined via the ":" delimiter.
Here an example:

pcie_mode=RP:EP:EP

This way, PCIe port 0 will be configured as rootpoint, PCIe port 1 and 2
as endpoint.

Per default Yucca will be configured as:
pcie_mode=RP:EP:EP

Per default Katmai will be configured as:
pcie_mode=RP:RP:REP

Per default Kilauea will be configured as:
pcie_mode=RP:RP

Signed-off-by: Tirumala R Marri <tmarri@amcc.com>
Signed-off-by: Stefan Roese <sr@denx.de>