Including debug ramdisk files in base_vendor.mk

Debug ramdisk files should exist for all devices.
Adding those debug ramdisk files in the base_vendor.mk.

  * https://source.android.com/compatibility/vts/vts-on-gsi

Bug: 193565271
Test: `lunch aosp_flame-userdebug`, `make bootimage_debug` then
      checks the output under $OUT/debug_ramdisk/.
Test: Performs the same check for `lunch aosp_bramble-userdebug`.
Change-Id: Id32a53da9a3d5b17ffd05449669c6aa17aec0dfa