net/9p: p9_idpool_get return -1 on error

We need to return -1 on error. Also handle error properly

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
diff --git a/net/9p/util.c b/net/9p/util.c
index da6af81..9c1c934 100644
--- a/net/9p/util.c
+++ b/net/9p/util.c
@@ -93,7 +93,7 @@
 
 retry:
 	if (idr_pre_get(&p->pool, GFP_NOFS) == 0)
-		return 0;
+		return -1;
 
 	spin_lock_irqsave(&p->lock, flags);