staging: vt6656: [BUG] BBvUpdatePreEDThreshold Always set sensitivity on bScanning

byBBPreEDIndex value is initially 0, this means that from
cold BBvUpdatePreEDThreshold is never set.

This means that sensitivity may be in an ambiguous state,
failing to scan any wireless points or at least distant ones.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>