iwlwifi: dbg: move debug recording stop from trans to op mode

The op mode should stop the debug recording and not the transport layer.
Rename iwl_fwrt_stop_device into iwl_fw_dbg_stop_sync and move the debug
stop recording to it.

Signed-off-by: Shahar S Matityahu <shahar.s.matityahu@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>