wlcore: fix interrogate command length

Change interrogate command prototype to have command size
and returned buffer length.
This fixes the issue when command parameters are needed to
be passed to FW in addition to acx header as in the case with
get RSSI command, where role_id has to be passed.

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