add missing lance_* exports

This patch fixes the following build error:

<--  snip  -->

...
  Building modules, stage 2.
  MODPOST 1203 modules
ERROR: "lance_open" [drivers/net/mvme147.ko] undefined!
ERROR: "lance_close" [drivers/net/mvme147.ko] undefined!
ERROR: "lance_tx_timeout" [drivers/net/mvme147.ko] undefined!
ERROR: "lance_set_multicast" [drivers/net/mvme147.ko] undefined!
ERROR: "lance_start_xmit" [drivers/net/mvme147.ko] undefined!
...
make[2]: *** [__modpost] Error 1

<--  snip  -->

Reported-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>