This patch is resolving Coverity hits where padding in a structure could
be used uninitialized.

- Initialize fwd_cmd.pad/2 before ixgbe_calculate_checksum()

- Initialize buffer.pad2/3 before ixgbe_hic_unlocked()
Signed-off-by: NEmil Tantilov <emil.s.tantilov@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>