i40e: check asq alive before notify

Driver needs to make sure the send queue is alive before
trying to use it.

Chagne-Id: I9bd1f6159c45c98e63f562e3a8dfb57edfe50e13
Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>