staging: fix silicom dependencies and build errors

Fix kconfig dependencies in silicom.  Fixes these build errors:

ERROR: "init_net" [drivers/staging/silicom/bypasslib/bypass.ko] undefined!
ERROR: "register_netdevice_notifier" [drivers/staging/silicom/bpctl_mod.ko] undefined!
ERROR: "unregister_netdevice_notifier" [drivers/staging/silicom/bpctl_mod.ko] undefined!
ERROR: "init_net" [drivers/staging/silicom/bpctl_mod.ko] undefined!
ERROR: "netdev_info" [drivers/net/mii.ko] undefined!
ERROR: "netif_carrier_on" [drivers/net/mii.ko] undefined!
ERROR: "netif_carrier_off" [drivers/net/mii.ko] undefined!

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>