qla2xxx: Prevent multiple firmware dump collection for ISP27XX.

For ISP27XX, driver will capture new firmware dump even if there is
one already collected. Prevent this from happening by checking
fw_dumped flag.

Signed-off-by: Giridhar Malavali <giridhar.malavali@qlogic.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@qlogic.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>