[SPARC64]: Serial Console for E250 Patch

From: Eddie C. Dost <ecd@brainaid.de>

I have the following patch for serial console over the RSC
(remote system controller) on my E250 machine. It basically adds
support for input-device=rsc and output-device=rsc from OBP, and
allows 115200,8,n,1,- serial mode setting.

Signed-off-by: David S. Miller <davem@davemloft.net>