pasemi_mac: clear out old errors on interface open

pasemi_mac: clear out old errors on interface open

Clear out any pending errors when an interface is brought up. Since the bits
are sticky, they might be from interface shutdown time after firmware has
used it, etc.

Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Jeff Garzik <jeff@garzik.org>