iwlwifi: dbg: debug recording stop and restart command remove

The 0xF6 command used to start and stop the recording from 22560 devices
was removed. This is causing an assert when the driver tries to alter
the recording state.
Remove the use of the command.

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