Staging: batman-adv: depend on NET instead of PACKET in Kconfig

The code which uses the raw packet sockets was removed. The only related
dependencies are the skb and netdev handling code. This is provided by
NET in Kconfig.

Signed-off-by: Sven Eckelmann <sven.eckelmann@gmx.de>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>