[PATCH] sky2: fix ram buffer for Yukon FE rev 2

Fix problems with Yukon FE rev 2 chipset. Don't cut and paste bugs in from
sk98lin driver. Change how the ram buffer is divided up, and make the math
clearer. Also, set the thresholds where rx takes precedence. The threshold
values are just guesses at this point, it might be worth tuning them later.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>