Revert "fix soc-core's inverse range and let IQaudIO DAC use this fixed SOC_DOUBLE_R_RANGE_TLV support"
Revert "Fix volsw_range functions so SOC_DOUBLE_R_RANGE_TLV works."
Revert "Add IQaudIO Sound Card support for Raspberry Pi"
Add IQaudIO Sound Card support for Raspberry Pi
soc-core: Fix volsw_range funcs so SOC_DOUBLE_R_RANGE_TLV works.

This is so that the correct range of values as specified
with the SOC_DOUBLE_R_RANGE_TLV macro are sent to the
hardware for both the normal and invert cases.
pcm512x: Use a range macro for Volume and rename to PCM.

This allows limiting the output gain to avoid clipping in the
DAC ouput stages.
Merge pull request #654 from hmbedded/rpi-3.15.y

 Fix for issue: 3.15.6 - error compiling pcm512 sound drivers #641