scsi: fix pmcraid build errors

pmcraid should depend on NET since it uses netlink interfaces.
This fixes multiple build errors when CONFIG_NET is not enabled:

ERROR: "genl_register_family" [drivers/scsi/pmcraid.ko] undefined!
ERROR: "genl_unregister_family" [drivers/scsi/pmcraid.ko] undefined!
ERROR: "nla_put" [drivers/scsi/pmcraid.ko] undefined!
ERROR: "init_net" [drivers/scsi/pmcraid.ko] undefined!
ERROR: "__alloc_skb" [drivers/scsi/pmcraid.ko] undefined!
ERROR: "netlink_broadcast" [drivers/scsi/pmcraid.ko] undefined!
ERROR: "kfree_skb" [drivers/scsi/pmcraid.ko] undefined!
ERROR: "skb_put" [drivers/scsi/pmcraid.ko] undefined!

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Anil Ravindranath <anil_ravindranath@pmc-sierra.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>