nfs: Define NFS_RDMA_PORT

The NFS/RDMA port assignment is specified in Section 9 of RFC 8267.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

include/uapi/linux/nfs.h

@@ -12,6 +12,7 @@
 
 #define NFS_PROGRAM	100003
 #define NFS_PORT	2049
+#define NFS_RDMA_PORT	20049
 #define NFS_MAXDATA	8192
 #define NFS_MAXPATHLEN	1024
 #define NFS_MAXNAMLEN	255