[SCSI] qla2xxx: Add loopback IDC-TIME-EXTEND aen handling support.

Earlier IDC-TIME-EXTEND aen was a nop and ignored by driver.
We now have to handle the aen so that other protocol drivers can use time
extension during some loopback operations.

Signed-off-by: Santosh Vernekar <santosh.vernekar@qlogic.com>
Signed-off-by: Saurav Kashyap <saurav.kashyap@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>