ASoC: wcd9335: Add 8KHz sample rate support on VI feedback path

Speaker protection algorithm uses VI feedback path samples for
gain calculation. VI feedback path on WCD9335 operates at 8KHz
sample rate. Add support for 8KHz sample rate on VI feedback
patch on WCD9335 codec.

Change-Id: Ie89748f7d5eb84b3e20802ace5649052d4553319
Signed-off-by: Sudheer Papothi <spapothi@codeaurora.org>