scsi: fix build errors, SCSI_FC_ATTRS needs to depend on SCSI && NET

Fix build errors when CONFIG_SCSI_NETLINK is enabled but
CONFIG_NET is not enabled:

drivers/built-in.o: In function `scsi_nl_rcv_msg':
scsi_netlink.c:(.text+0x1850fa): undefined reference to `netlink_ack'
scsi_netlink.c:(.text+0x185105): undefined reference to `skb_pull'
scsi_netlink.c:(.text+0x18515d): undefined reference to `netlink_capable'
drivers/built-in.o: In function `scsi_netlink_init':
(.text+0x185244): undefined reference to `init_net'
drivers/built-in.o: In function `scsi_netlink_init':
(.text+0x185258): undefined reference to `__netlink_kernel_create'
drivers/built-in.o: In function `scsi_netlink_exit':
(.text+0x185291): undefined reference to `netlink_kernel_release'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Anish Bhatt <anish@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>