The machine driver bdw-rt5650 (for Google buddy) supports 2 or 4-channel
recording while other two drivers support only 2-channel recording. HW
constraints are implemented to reflect the hardware limitation on BDW
platform.
Changes since v1:
- Change the patch title.
- Remove the DUAL_CHANNEL and QUAD_CHANNEL macros which are too obvious.
- Follow the naming convertion, using 'bdw_rt5650_' and 'bdw_rt5677_' to
name startup functions.
- Refine the comments in startup functions.
- Redesign the bdw_rt5650_fe_startup() function for readability.
- Add an assignment to initialize runtime->hw.channels_max variable.