mtd: cfi_cmdset_0002, fix lock imbalance

Stanse found a double unlock in get_chip. get_chip is called with
chip->mutex held and caller is responsible for unlocking it too.

Do not unlock the lock in get_chip on a fail path. This would mean
a double unlock.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/chips/cfi_cmdset_0002.c

@@ -569,7 +569,6 @@ static int get_chip(struct map_info *map, struct flchip *chip, unsigned long adr
 
 			if (time_after(jiffies, timeo)) {
 				printk(KERN_ERR "Waiting for chip to be ready timed out.\n");
-				spin_unlock(chip->mutex);
 				return -EIO;
 			}
 			spin_unlock(chip->mutex);