i40e: fix trivial typo in naming of i40e_sync_filters_subtask

A comment incorrectly referred to i40e_vsi_sync_filters_subtask which
does not actually exist. Reference the correct function instead.

Change-ID: I6bd805c605741ffb6fe34377259bb0d597edfafd
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>