xprtrdma: Boost client's max slot table size to match Linux server

I've heard rumors of an NFS/RDMA server implementation that has a
default credit limit of 1024. The client's default setting remains
at 128.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

include/linux/sunrpc/xprtrdma.h

@@ -49,9 +49,9 @@
  * fully-chunked NFS message (read chunks are the largest). Note only
  * a single chunk type per message is supported currently.
  */
-#define RPCRDMA_MIN_SLOT_TABLE	(2U)
+#define RPCRDMA_MIN_SLOT_TABLE	(4U)
 #define RPCRDMA_DEF_SLOT_TABLE	(128U)
-#define RPCRDMA_MAX_SLOT_TABLE	(256U)
+#define RPCRDMA_MAX_SLOT_TABLE	(16384U)
 
 #define RPCRDMA_MIN_INLINE  (1024)	/* min inline thresh */
 #define RPCRDMA_DEF_INLINE  (4096)	/* default inline thresh */