[SCSI] zfcp: Remove duplicated code from zfcp_ccw_set_online

The steps for setting the zfcp_adapter online are the same in
zfcp_ccw_set_online and zfcp_ccw_activate. Remove the code duplication
by calling zfcp_ccw_activate from zfcp_ccw_set_online.

Reviewed-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>