Staging: vt6656: Clean up switching to power saving mode.

When switching to power saving mode we only need to notify
the receiver when in infrastructure mode.

Signed-off-by: Philip Worrall <philip.worrall@googlemail.com>
Reviewed-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>