igc: Allow for Flex Filters to be installed

Allows Flex Filters to be installed.

The previous restriction to the types of filters that can be installed
can now be lifted.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Tested-by: Dvora Fuxbrumer <dvorax.fuxbrumer@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>