db845c: Set baud rate for serial console am: c2840b75d1

Original change: https://android-review.googlesource.com/c/device/linaro/dragonboard/+/2261884

Change-Id: Idcea91b2eba49f97fa1600550cee10f3c3e150c0
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>