The initialization of the echo detector should always signal that the input audio is mono.
The initialization of the echo detector should always signal that the input audio is mono.

Since we always pass in the first audio channel, we should always pass 1 as the number of channels in the initialization function.

Bug: webrtc:8732
Change-Id: I978edb125d7cc701a5e07193256327908be00560
Reviewed-on: https://webrtc-review.googlesource.com/69660
Commit-Queue: Ivo Creusen <ab68de427b265c46935558af10238a1ba5449aeb@webrtc.org>
Reviewed-by: Per Åhgren <3616c2c8a2c30a769c5419f89b4a810ea6e2f079@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#22885}
ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc