dragonboards: Move firmware files to external vendor overlay package am: fbd3fbbd53 am: cf166be72f am: dc10a27106 am: 88ccff8bd3

Original change: https://android-review.googlesource.com/c/device/linaro/dragonboard/+/1918441

Change-Id: I96b5a02ed3e21dbece5886ada91d23d2adabd861