Canceling the periodic timestamp work should be
done in the opposite flow to where it was started.
This also prevents from sending the MARKER command
during the mac_stop flow - causing a false queue hang
(FW is no longer there to send a response).

Fixes: 93b167c1 ("iwlwifi: runtime: sync FW and host clocks for logs")
Signed-off-by: Shaul Triebitz <shaul.triebitz@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>