rpcrdma: Merge svcrdma and xprtrdma modules into one

Bi-directional RPC support means code in svcrdma.ko invokes a bit of
code in xprtrdma.ko, and vice versa. To avoid loader/linker loops,
merge the server and client side modules together into a single
module.

When backchannel capabilities are added, the combined module will
register all needed transport capabilities so that Upper Layer
consumers automatically have everything needed to create a
bi-directional transport connection.

Module aliases are added for backwards compatibility with user
space, which still may expect svcrdma.ko or xprtrdma.ko to be
present.

This commit reverts commit 2e8c12e1b7 ("xprtrdma: add separate
Kconfig options for NFSoRDMA client and server support") and
provides a single CONFIG option for enabling the new module.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

net/sunrpc/Kconfig

@@ -48,28 +48,16 @@ config SUNRPC_DEBUG
 
 	  If unsure, say Y.
 
-config SUNRPC_XPRT_RDMA_CLIENT
-	tristate "RPC over RDMA Client Support"
+config SUNRPC_XPRT_RDMA
+	tristate "RPC-over-RDMA transport"
 	depends on SUNRPC && INFINIBAND && INFINIBAND_ADDR_TRANS
 	default SUNRPC && INFINIBAND
 	help
-	  This option allows the NFS client to support an RDMA-enabled
-	  transport.
+	  This option allows the NFS client and server to use RDMA
+	  transports (InfiniBand, iWARP, or RoCE).
 
-	  To compile RPC client RDMA transport support as a module,
-	  choose M here: the module will be called xprtrdma.
+	  To compile this support as a module, choose M. The module
+	  will be called rpcrdma.ko.
 
-	  If unsure, say N.
-
-config SUNRPC_XPRT_RDMA_SERVER
-	tristate "RPC over RDMA Server Support"
-	depends on SUNRPC && INFINIBAND && INFINIBAND_ADDR_TRANS
-	default SUNRPC && INFINIBAND
-	help
-	  This option allows the NFS server to support an RDMA-enabled
-	  transport.
-
-	  To compile RPC server RDMA transport support as a module,
-	  choose M here: the module will be called svcrdma.
-
-	  If unsure, say N.
+	  If unsure, or you know there is no RDMA capability on your
+	  hardware platform, say N.