[SCSI] zfcp: clear adapter status flags during adapter shutdown

In some cases we did not reset some adapter status flags properly.
This patch clears these flags during FCP adapter shutdown.

Signed-off-by: Volker Sameske <sameske@de.ibm.com>
Signed-off-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>