ppc4xx: Update PMC440 board support

This patch brings PMC440 board support up to date:

- fix GPIO configuration
- add misc_init_f()
- use better values for usbact variable
- fix USB 2.0 phy reset sequence
- shrink BAR2 to save PCI address space
- add FDT support

Signed-off-by: Matthias Fuchs <matthias.fuchs@esd-electronics.com>
Signed-off-by: Stefan Roese <sr@denx.de>