iwlwifi: mvm: make sure state isn't in d0i3 when stopping fw monitor

In case platform is in d0i3 - make sure it is awake when
writing the registers to stop the monitor when collecting FW
debug data. Plus, remove unneeded mutex locking currently
done.

Signed-off-by: Liad Kaufman <liad.kaufman@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>