Drop rb5-userdebug build target and use db845c-userdebug for RB5

We have been using db845c-userdebug target builds to support
DB845c (RB3) and RB5 devboards for a long time now. So it is
time to formally drop rb5-userdebug build target from AOSP.

The RB5 flashing instructions in installer/rb5/ remain the same.
The device documentation as available from "Android Reference
Boards" page https://source.android.com/docs/setup/create/devices
is already updated.

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Change-Id: I2af594bfd23f7b963d65e9b50a38389b292f56cf
10 files changed