i40e: propagate properly

i40e_sync_vsi_filters() is the surly teenager of this driver. It says
it's going to report errors, but it doesn't actually do that most of the
time. And when it does, it leaves a mess.

Change this function to have a common exit point so it will properly
release the busy lock on the VSI. Propagate errors to the callers.
Finally, adjust a few callers to check for and deal with errors from
this function.

Change-ID: Ic6af4956491e72402ebb3c538a3c31a0ad7f8667
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>