Camera: Don't drop preview buffers during video

In case the camera device supports ZSL, avoid dropping
preview buffers while video recording is active. Preview
must not get interrupted in this case.

Bug: 117640175
Test: Manual using application, Camera CTS
Change-Id: I9021b4c46428e008298ddef0a86972640b0afa41
Merged-In: I9021b4c46428e008298ddef0a86972640b0afa41
(cherry picked from commit 6c79c9aa)