SUNRPC: display human-readable procedure name in rpc_iostats output

Add fields to the rpc_procinfo struct that allow the display of a
human-readable name for each procedure in the rpc_iostats output.

Also fix it so that the NFSv4 stats are broken up correctly by
sub-procedure number.  NFSv4 uses only two real RPC procedures:
NULL, and COMPOUND.

Test plan:
Mount with NFSv2, NFSv3, and NFSv4, and do "cat /proc/self/mountstats".

Signed-off-by: Chuck Lever <cel@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/net/sunrpc/pmap_clnt.c b/net/sunrpc/pmap_clnt.c
index 332cc5d..efa00bd 100644
--- a/net/sunrpc/pmap_clnt.c
+++ b/net/sunrpc/pmap_clnt.c
@@ -261,6 +261,8 @@
 	  .p_decode		= (kxdrproc_t) xdr_decode_bool,
 	  .p_bufsiz		= 4,
 	  .p_count		= 1,
+	  .p_statidx		= PMAP_SET,
+	  .p_name		= "SET",
 	},
 [PMAP_UNSET] = {
 	  .p_proc		= PMAP_UNSET,
@@ -268,6 +270,8 @@
 	  .p_decode		= (kxdrproc_t) xdr_decode_bool,
 	  .p_bufsiz		= 4,
 	  .p_count		= 1,
+	  .p_statidx		= PMAP_UNSET,
+	  .p_name		= "UNSET",
 	},
 [PMAP_GETPORT] = {
 	  .p_proc		= PMAP_GETPORT,
@@ -275,6 +279,8 @@
 	  .p_decode		= (kxdrproc_t) xdr_decode_port,
 	  .p_bufsiz		= 4,
 	  .p_count		= 1,
+	  .p_statidx		= PMAP_GETPORT,
+	  .p_name		= "GETPORT",
 	},
 };