9p: Reduce object size with CONFIG_NET_9P_DEBUG

Reduce object size by deduplicating formats.

Use vsprintf extension %pV.
Rename P9_DPRINTK uses to p9_debug, align arguments.
Add function for _p9_debug and macro to add __func__.
Add missing "\n"s to p9_debug uses.
Remove embedded function names as p9_debug adds it.
Remove P9_EPRINTK macro and convert use to pr_<level>.
Add and use pr_fmt and pr_<level>.

$ size fs/9p/built-in.o*
   text	   data	    bss	    dec	    hex	filename
  62133	    984	  16000	  79117	  1350d	fs/9p/built-in.o.new
  67342	    984	  16928	  85254	  14d06	fs/9p/built-in.o.old
$ size net/9p/built-in.o*
   text	   data	    bss	    dec	    hex	filename
  88792	   4148	  22024	 114964	  1c114	net/9p/built-in.o.new
  94072	   4148	  23232	 121452	  1da6c	net/9p/built-in.o.old

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
diff --git a/net/9p/protocol.c b/net/9p/protocol.c
index 55e10a9..9ee48cb 100644
--- a/net/9p/protocol.c
+++ b/net/9p/protocol.c
@@ -534,7 +534,7 @@
 
 	ret = p9pdu_readf(&fake_pdu, clnt->proto_version, "S", st);
 	if (ret) {
-		P9_DPRINTK(P9_DEBUG_9P, "<<< p9stat_read failed: %d\n", ret);
+		p9_debug(P9_DEBUG_9P, "<<< p9stat_read failed: %d\n", ret);
 		trace_9p_protocol_dump(clnt, &fake_pdu);
 	}
 
@@ -558,8 +558,8 @@
 	pdu->size = size;
 
 	trace_9p_protocol_dump(clnt, pdu);
-	P9_DPRINTK(P9_DEBUG_9P, ">>> size=%d type: %d tag: %d\n", pdu->size,
-							pdu->id, pdu->tag);
+	p9_debug(P9_DEBUG_9P, ">>> size=%d type: %d tag: %d\n",
+		 pdu->size, pdu->id, pdu->tag);
 
 	return err;
 }
@@ -585,7 +585,7 @@
 	ret = p9pdu_readf(&fake_pdu, clnt->proto_version, "Qqbs", &dirent->qid,
 			  &dirent->d_off, &dirent->d_type, &nameptr);
 	if (ret) {
-		P9_DPRINTK(P9_DEBUG_9P, "<<< p9dirent_read failed: %d\n", ret);
+		p9_debug(P9_DEBUG_9P, "<<< p9dirent_read failed: %d\n", ret);
 		trace_9p_protocol_dump(clnt, &fake_pdu);
 		goto out;
 	}