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/fs/9p/fid.c b/fs/9p/fid.c
index 85b67ff..da8eefb 100644
--- a/fs/9p/fid.c
+++ b/fs/9p/fid.c
@@ -45,8 +45,8 @@
 {
 	struct v9fs_dentry *dent;
 
-	P9_DPRINTK(P9_DEBUG_VFS, "fid %d dentry %s\n",
-					fid->fid, dentry->d_name.name);
+	p9_debug(P9_DEBUG_VFS, "fid %d dentry %s\n",
+		 fid->fid, dentry->d_name.name);
 
 	dent = dentry->d_fsdata;
 	if (!dent) {
@@ -79,8 +79,8 @@
 	struct v9fs_dentry *dent;
 	struct p9_fid *fid, *ret;
 
-	P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n",
-		dentry->d_name.name, dentry, uid, any);
+	p9_debug(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n",
+		 dentry->d_name.name, dentry, uid, any);
 	dent = (struct v9fs_dentry *) dentry->d_fsdata;
 	ret = NULL;
 	if (dent) {