motorola-potter: use msm-firmware-loader & cleanups

I have migrate motorola-potter to msm-firmware-loader and soc-qcom-msm8953 and do some clean ups in device and firmware package. TODO:

• There will be some soc-qcom-msm8953-ucm related changes https://github.com/msm8953-mainline/alsa-ucm-conf/pull/11
• There will be some kernel changes related to audio https://github.com/msm8953-mainline/linux/pull/179
• For modem it needs MR !4677 (closed) or !4747 (merged)