wlcore: Allow stopping fw log in recovery

The FW panic log is read during recovery work.
It has to be stopped properly before reading. otherwise,
inconsistent data might be read which cause the driver
to freeze.

__wlcore_cmd_send has to work for the special case of
CMD_STOP_FWLOGGER, while in recovery, in order to stop
the fw log before it is read.

Signed-off-by: Barak Bercovitz <barak@wizery.com>
Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>