RDMA: Add netlink infrastructure

Add basic RDMA netlink infrastructure that allows for registration of
RDMA clients for which data is to be exported and supplies message
construction callbacks.

Signed-off-by: Nir Muchtar <nirm@voltaire.com>

[ Reorganize a few things, add CONFIG_NET dependency.  - Roland ]

Signed-off-by: Roland Dreier <roland@purestorage.com>
diff --git a/drivers/infiniband/Kconfig b/drivers/infiniband/Kconfig
index 6e35ecc..0f9a84c 100644
--- a/drivers/infiniband/Kconfig
+++ b/drivers/infiniband/Kconfig
@@ -2,6 +2,7 @@
 	tristate "InfiniBand support"
 	depends on PCI || BROKEN
 	depends on HAS_IOMEM
+	depends on NET
 	---help---
 	  Core support for InfiniBand (IB).  Make sure to also select
 	  any protocols you wish to use as well as drivers for your