UBI: remove ubi_devices_cnt

This global variablea is not really needed, remove it

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c
index 12777da..7697eda 100644
--- a/drivers/mtd/ubi/cdev.c
+++ b/drivers/mtd/ubi/cdev.c
@@ -60,7 +60,7 @@
 {
 	int i;
 
-	for (i = 0; i < ubi_devices_cnt; i++)
+	for (i = 0; i < UBI_MAX_DEVICES; i++)
 		if (ubi_devices[i] && MAJOR(ubi_devices[i]->cdev.dev) == major)
 			return ubi_devices[i];
 	BUG();