libeffects: Fixed bit mismatch seen with 3 channel input

The output for a 3 channel input is not bit-exact with that of
2 channel input when concert surround is enabled and tested using lvmtest.

Test: local native test (lvmtest)
Bug: 124085228
Change-Id: Icb2d1d5d858be0c37cb11dd3734f8a6244d3cc1c
2 files changed