iwlwifi: dbg_ini: make memory dump get_size handler include headers

Make the get size handler of iwl_dump_ini_mem_ops include the total
size of the region. It is needed for fifos dumping.

Signed-off-by: Shahar S Matityahu <shahar.s.matityahu@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>