SOUND: Add WM8994 codec

This patch adds driver for audio codec WM8994

Signed-off-by: R. Chandrasekar <rcsekar@samsung.com>
Signed-off-by: Rajeshwari Shinde <rajeshwari.s@samsung.com>
Acked-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>