i40e: always remove old filter when adding new FDir filter

The previous code relied on i40e_match_fdir_input_set to determine when
determining whether to free the old filter. Change this code so that we
simply unconditionally delete the old filter, even if it's identical to
the new filter. This ensures that we don't leak any memory, and that we
always update the filters as expected.

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>