ppc7xx: Update CPCI750 board

This small CPCI750 update extends the board specific command
"show_config" to display the Marvell strapping registers and
extends the PCI IDE controller.

Signed-off-by: Reinhard Arlt <reinhard.arlt@esd-electronics.com>
Signed-off-by: Stefan Roese <sr@denx.de>