dragonboard: fstab.common: Set metadata as first_stage_mount to resolve adb remount overlay persistence issues

PeterC reported adb remount was not working properly,
and I noticed we had the same issue on HiKey960 recently
due to metadata not being set as first_stage_mount in fstab.

So this patch makes a similar change to fix the issue here.

Test: Passes system/core/fs_mgr/tests/adb-remount-test.sh
Signed-off-by: John Stultz <john.stultz@linaro.org>
Change-Id: If92f7810ff045ff58505a1af6829ec529a289cc2
1 file changed