scsi_netlink : Make SCSI_NETLINK dependent on NET instead of selecting NET

Required for avoiding recursive dependencies in the Kconfig, brought out
by fixing randconfig error for bnx2i/bnx2fc in the patch that follows.
As suggested by Randy Dunlap

Signed-off-by: Anish Bhatt <anish@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>