[MIPS] Cobalt: Qube1 has no serial port so don't use it

Because Qube1 doesn't have a serial chip waiting for transmit fifo empty
takes forever, which isn't a good idea. No prom_putchar/early console
for Qube1 fixes this.

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Acked-by: Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>