Merge "Enable serial console on dragonboard devices." am: b539f3164c

Original change: https://android-review.googlesource.com/c/device/linaro/dragonboard/+/2103407

Change-Id: I26343888cf74615966241aa50d25409fdb9bb306
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>