This patch introduces the CAIF HSI Protocol Driver for the
CAIF Link Layer.

This driver implements a platform driver to accommodate for a
platform specific HSI devices. A general platform driver is not
possible as there are no HSI side Kernel API defined.
Signed-off-by: NSjur Brændeland <sjur.brandeland@stericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>