dt-bindings: Add asc vendor

All Sensors Corporation is a manufacturer of MEMS piezoresitive
ultra low pressure sensors and pressure transducers.

Signed-off-by: Tomislav Denis <tomislav.denis@avl.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>