iwlwifi: do not reload fw if WiMAX own the RF

For WiFi/WiMAX combo devices, if WiMAX own the RF, WiFi driver
try to access RF and fail. This is the W/A to To avoid WiFi keep
reloading firmware and try to access RF again.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>