smartfs: return -ENOTTY if ioctl command is not found

The upper layer expects -ENOTTY is returned if ioctl command is not
found in file system specific implementation.

Signed-off-by: Michal Lenc <michallenc@seznam.cz>

fs/smartfs/smartfs_smart.c

@@ -1035,7 +1035,7 @@ static int smartfs_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
         }
         break;
       default:
-        ret = -ENOSYS;
+        ret = -ENOTTY;
         break;
     }