Account for stride when calculating buffer size

https://webrtc-review.googlesource.com/c/src/+/240680 made encoder aware of stride and slice height of input buffer but calculation of buffer size passed to queueInputBuffer() was not updated.

Bug: webrtc:13427
Change-Id: Iba8687f56eda148ac67b331d35c45317a4ec5c59
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/301321
Reviewed-by: Mirta Dvornicic <mirtad@webrtc.org>
Commit-Queue: Sergey Silkin <ssilkin@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#39895}