i40e: Fix the EMPR interrupt received handling

We shouldn't trigger another EMPR when we receive an EMPR event.
This patch handles EMPR event reception with a different state
so that we can do the right thing for NVM.

Change-ID: I9cac70b3658600f016a65beb6fb157e1c1f9adf9
Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Tested-by: Jim Young <james.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>