[SCSI] zfcp: Remove adapter list

After the latest changes, the list of FCP devices is only used to
lookup the adapter for requests from the actcli tool. Change this to
use the lookup function in the cio layer. Now we can remove the
adapter list and have one place less to use the global config_lock.

Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Acked-by: Felix Beck <felix@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>