Revert "Remove vendor partition"

Revert submission 2625691

Reason for revert: b/287283650

Reverted changes: /q/submissionid:2625691

Change-Id: I974c2b96230507d4360f4333608c22e219af9667
diff --git a/microdroid/fstab.microdroid b/microdroid/fstab.microdroid
index 9478c7c..25d82cc 100644
--- a/microdroid/fstab.microdroid
+++ b/microdroid/fstab.microdroid
@@ -1 +1,2 @@
 system /system ext4 noatime,ro,errors=panic wait,slotselect,avb=vbmeta,first_stage_mount,logical
+vendor /vendor ext4 noatime,ro,errors=panic wait,slotselect,avb=vbmeta,first_stage_mount,logical