ASoC: wcd9306: use hwdep nodes to get calibration

Use hwdep node to use calibration and at the same
time keep the code backward compatible. Codec
driver can still use request_firmware to get the
calibration if hwdep is not available.

Change-Id: Iea2cf1ff753a5750919b201ded63cd8840a40baf
Signed-off-by: Yeleswarapu Nagaradhesh <nagaradh@codeaurora.org>