[SCSI] qla4xxx: set device state as per Link UP and LINK DOWN

Link Down -> Mark all devices missing
 Previously, the driver took no action on a Link Down,
 and waited for the I/O on a dead connection to timeout
 in the firmware before marking the DDB missing.

Link Up -> Mark all devices online
 F/W will do auto login to all the devices only once.
 After that its the responsibility of the driver to
 relogin to devices whenever there is :
        * Any sort of connection failure or
        * KATO expires indicating target has logged out or
        * I/O times out etc.

Signed-off-by: Vikas Chaudhary <vikas.chaudhary@qlogic.com>
Signed-off-by: Karen Higgins <karen.higgins@qlogic.com>
Signed-off-by: Ravi Anand <ravi.anand@qlogic.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>