ASoC: codecs: qualcomm move gain to S8_TLV

Merge series from Srinivas Kandagatla <srinivas.kandagatla@linaro.org>:

Move all the digital and IIR gains form using SX_TLV to S8_TLV,
these gains are actually 8 bit gains with 7th signed bit and
ranges from -84dB to +40dB

Tested on DB410c with Headset playback