scsi: qedf: fixup locking in qedf_restart_rport()

fc_rport_create() needs to be called with disc_mutex held.  And we should
re-assign the 'rdata' pointer in case it got changed.

Signed-off-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Saurav Kashyap <skashyap@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>