The sink has different frame size than the sink input, so
the max_request and max_rewind values of the sink input need
to be converted when setting the sink max_request and
max_rewind values.
The conversion is already done correctly in
sink_input_update_max_request_cb() and
sink_input_update_max_rewind_cb().
It provides a virtual surround sound effect.
v2: Normalize hrir to avoid clipping, some cleanups
v3: use fabs, not abs
v4: implement changes proposed by Tanu Kaskinen
v5: likewise
v6: use channel map from hrir file
v7: remove hrir_ss and hrir_map form userdata
v8: update naming of sink
