Fixed typo in max macroblock frame size.
Fixed typo in max macroblock frame size.

Bug: webrtc:9134
Change-Id: I218342f608912a9fe0ded374e26274b0c9f6d678
Reviewed-on: https://webrtc-review.googlesource.com/71520
Reviewed-by: Magnus Jedvert <9507adee858471ab168c339dc72b814b168c081b@webrtc.org>
Commit-Queue: Kári Helgason <79949f6d84ac41ff1f64c59fd5a554be5ff12a02@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#23031}
TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc