Make use of the device property API in this driver so that both OF based
systems and ACPI based systems can use this driver.
Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Suggested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>