i40e: clean event descriptor before use

In one obscure corner case, it was possible to clear the NVM update wait
flag when no update_done message was actually received.  This patch
cleans the event descriptor before use, and moves the opcode check to
where it won't get done if there was no event to clean.

Also update copyright year in file headers.

Change-ID: I68bbc41965e93f4adf07cbe98b9dfd63d41509a4
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>