i40e: clean whole mac filter list

Clean the whole mac filter list when resetting after an intermediate
add or delete push to the firmware.  The code had evolved from using
a list from the stack to a heap allocation, but the memset() didn't
follow the change correctly.  This now cleans the whole list rather
that just part of the first element.

Change-ID: I4cd03d5a103b7407dd8556a3a231e800f2d6f2d5
Reported-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>