[PATCH] Correct xircom_cb use of CONFIG_NET_POLL_CONTROLLER

xircom_cb.c does #if CONFIG_NET_POLL_CONTROLLER instead of #ifdef,
resulting in drivers/net/tulip/xircom_cb.c:120:5: warning:
"CONFIG_NET_POLL_CONTROLLER" is not defined.

Signed-off-by: Keith Owens <kaos@sgi.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>