i40e: use unsigned printf format specifier for active_filters count

Replace the %d specifier used for printing vsi->active_filters and
vsi->promisc_threshold with an unsigned %u format specifier. While it is
unlikely in practice that these values will ever reach such a large
number they are unsigned values and thus should not be interpreted as
negative numbers.

Change-ID: Iff050fad5a1c8537c4c57fcd527441cd95cfc0d4
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>