nfs: Remove invalid tk_pid from debug message

Before rpc_run_task(), tk_pid is uninitiated as 0 always.

Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index d70228a..1da68d3 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -636,9 +636,8 @@
 
 	hdr->rw_ops->rw_initiate(hdr, &msg, rpc_ops, &task_setup_data, how);
 
-	dprintk("NFS: %5u initiated pgio call "
+	dprintk("NFS: initiated pgio call "
 		"(req %s/%llu, %u bytes @ offset %llu)\n",
-		hdr->task.tk_pid,
 		hdr->inode->i_sb->s_id,
 		(unsigned long long)NFS_FILEID(hdr->inode),
 		hdr->args.count,