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