ASoC: wcd9xxx: use hwdep node for codec calibration

currently codec driver uses request_firmware to get
calibration data but as this firmware file is also written by
userspace process after bootup, it is not recommended to
use request_firmware. ALSA core provides mechanism to get
hardware dependant data using hwdep nodes. Tomtom codec will
use aforementioned nodes to get calibration data from userspace.

Change-Id: Iace6e239029c7b0d93a5d61a0025ee551acf952f
Signed-off-by: Anish Kumar <kanish@codeaurora.org>