iwlwifi: mvm: ignore temperature updates in the RX statistics notification

If the firmware sends spontaneous DTS notfications with the
temperature (indicated in a TLV), we can ignore the temperature we get
in the RX statistics notifications.  This prevents potentially
handling the same temperature change twice.  It also ignores
notifications with temperature equal to 0 that happens from time to
time.

Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>