Add support for i386 architecture and AMD SC520 board
* Patch by Pierre Aubert, 12 Nov 2002:
Add support for DOS filesystem and booting from DOS floppy disk
Increase number of network RX buffers (PKTBUFSRX in
"include/net.h") for EEPRO100 based boards (especially SP8240)
which showed "Receiver is not ready" errors when U-Boot was
processing the receive buffers slower than the network controller
was filling them.
* Get rid of obsolete include/mpc74xx.h