iwlwifi: no need to refer to max_nrg_cck range value

max_nrg_cck value inside the sensitivity range structure is not needed
for sensitivity calibration.
Keep the parameter in sensitivity structure but set the value to "0" in case
needed in the future implementation.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>