Enable support for the onboard PATA PIO mode3 interface, which is one of
the boot devices supported by the CFE firmware with the Broadcom SWARM
board.  Include disk, CD-ROM and generic storage drivers.

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>