[PATCH] WAN: fix C101 card carrier handling

Hi,

One of my recent changes broke C101 carrier handling, this patch
fixes it. Also fixes an old TX underrun checking bug.

2.6.18 material. Please apply.
Thanks.

Signed-off-by: Krzysztof Halasa <khc@pm.waw.pl>
Signed-off-by: Jeff Garzik <jeff@garzik.org>