ASoC: wcd_cpe_core: Add support for dynamic image download

For supporting multiple algorithms on CPE, the cpe image needs to be
re-downloaded based on the algorithm. Add changes to expose sysfs
interface to accept cpe firmware image name and download the image with
the name provided at run time.

Change-Id: I0dfd71c45f87b75b694e5a82d66601db11544ee4
Signed-off-by: Bhalchandra Gajare <gajare@codeaurora.org>