i40e: let firmware catch the NVM busy error

The NVM update operations take time finish asynchronously, and follow-on
update requests need to wait for the current one to finish.  Early
firmware didn't handle this well, so the code had to track the busy state.
The released firmware handles the busy state correctly, returning
I40E_AQ_RC_EBUSY if an update is still in progress, so the code no longer
needs to track this.

Change-ID: I6e6b4adc26d6dcc5fd7adfee5763423858a7d921
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Acked-by: Greg Rose <gregory.v.rose@intel.com>
Tested-by: Jim Young <jamesx.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>