Add support for Seeq 8003 on Challenge S Mezz board.

Thanks to Jö Fahlke for donating hardware.

Signed-off-by: Ladislav Michl <ladis@linux-mips.org>

Forward porting of Ladis' 2.4 patch.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>