iwlwifi: mvm: support multiple firmware sections

Newer devices have two embedded CPUs, and the firwmare for
both of them is include in the .ucode file requested upon
enumeration.
An empty section with address=0xFFFFCCCC separates between
the sections intended for cpu1 and the sections intended
for cpu2.
Update the driver to parse the .ucode file with this format
and act accordingly.

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