wlcore: disable elp sleep while in plt mode

We now disable elp sleep during plt mode to allow normal operation of
plt tools such as calibrator.

Having elp_sleep enabled during plt mode is actually not required and
in fact it disrupt plt operations such as rx statistics etc.

Signed-off-by: Yair Shapira <yair.shapira@ti.com>
Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>