iwlwifi: support Signed firmware image and Dual CPUs

Support Signed firmware based on code signing system (CSS)
protocol and dual CPUs download,
the code recognize if there are more than one CPU and
if we need to operate the signed protocol according to
the ucode binary image

Signed-off-by: Eran Harary <eran.harary@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>