9p: strlen() doesn't count the terminator

This is an off by one bug because strlen() doesn't count the NULL
terminator.  We strcpy() addr into a fixed length array of size
UNIX_PATH_MAX later on.

The addr variable is the name of the device being mounted.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
index 98ce9bc..c85109d 100644
--- a/net/9p/trans_fd.c
+++ b/net/9p/trans_fd.c
@@ -948,7 +948,7 @@
 
 	csocket = NULL;
 
-	if (strlen(addr) > UNIX_PATH_MAX) {
+	if (strlen(addr) >= UNIX_PATH_MAX) {
 		P9_EPRINTK(KERN_ERR, "p9_trans_unix: address too long: %s\n",
 			addr);
 		return -ENAMETOOLONG;