wifi: iwlwifi: drop NULL pointer check in iwl_mvm_tzone_set_trip_temp()

wifi: iwlwifi: drop NULL pointer check in iwl_mvm_tzone_set_trip_temp()

Since 'tz_device' is an in-place member of 'struct iwl_mvm', it can't
be NULL and so relevant check may be dropped. Compile tested only.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Acked-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20231003092048.24998-1-dmantipov@yandex.ru
Signed-off-by: Johannes Berg <johannes.berg@intel.com>