wlcore: read fw panic log only in host mode

Reading FW panic log is only supported in host mode (SDIO)

Signed-off-by: Barak Bercovitz <barak@wizery.com>
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>