ASoC: qdsp6: q6common: Add qdsp6 helper functions

This patch adds some common helper functions like translating dsp error
to linux error codes and channel mappings etc.

These functions are used in all the following qdsp6 drivers.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-and-tested-by: Rohit kumar <rohitkr@codeaurora.org>
Reviewed-by: Banajit Goswami <bgoswami@codeaurora.org>
Signed-off-by: Mark Brown <broonie@kernel.org>