ASoC: qcom: Limit Digital gains on speaker

Merge series from srinivas.kandagatla@linaro.org:

Limit the speaker digital gains to 0dB so that the users will not damage them.
Currently there is a limit in UCM, but this does not stop the user form
changing the digital gains from command line. So limit this in driver
which makes the speakers more safer without active speaker protection in
place.

Apart from this there is also a range check fix in snd_soc_limit_volume
to allow setting this limit correctly.

Tested on Lenovo X13s.