s390/dasd: Remove dead return code checks

In dasd_term_IO() ccw_device_clear() is called and the return code is
checked afterwards. Though, the return codes -EIO and -EBUSY will never
be returned and can therefore be removed from the check.

In dasd_start_IO() the return code of either ccw_device_tm_start() or
ccw_device_start() is checked. However, neither of them returns
-ETIMEDOUT. Remove that check as well.

Signed-off-by: Jan Höppner <hoeppner@linux.vnet.ibm.com>
Acked-by: Stefan Haberland <sth@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>