qlcnic: diagnostics routine changes

Test and set diagnostics mode bit before starting
diagnostics tests. Stop diagnostics tests if adapter is resetting.

Signed-off-by: Sony Chacko <sony.chacko@qlogic.com>
Signed-off-by: Shahed Shaikh <shahed.shaikh@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>