iwlwifi: mvm: Fix warning message when exit thermal throttling

When NIC exit thermal throttling while having minimal tx-backoff
restriction, the warning message that indicate about that state
won't show up. Fixed.

Signed-off-by: Eytan Lifshitz <eytan.lifshitz@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>