[coreboot] SeaBIOS support for high-speed (EHCI) USB

[Kevin O'Connor]

Hi,

The latest SeaBIOS git now has support for EHCI USB controllers.  This
is in addition to the UHCI and OHCI support already in SeaBIOS.  To
obtain SeaBIOS, see:

http://seabios.org/Download

I've tested the EHCI support on my epia-cn.  Booting from USB drives
is now noticeably faster.

Currently SeaBIOS supports USB keyboards, USB hubs, and USB drives.

Help with testing on a wider range of hardware would be appreciated.

-Kevin