Revert^2 "init: Look for super partition only on a boot device"

This reverts commit 8d71220df28851a7dce351f86601958fdbc3e5ae.

Reason for revert: Fix for gcar emulator (basically all QEMU-based emulators) landed at aosp/3315253 and aosp/3160116.

Change-Id: If4eddd3f7e224c31019ad3bd752e2375c7567780
diff --git a/init/devices.h b/init/devices.h
index 6da1232..4df604d 100644
--- a/init/devices.h
+++ b/init/devices.h
@@ -133,6 +133,7 @@
     // `androidboot.partition_map=vdb,metadata;vdc,userdata` maps `vdb` to `metadata` and `vdc` to
     // `userdata`.
     static std::string GetPartitionNameForDevice(const std::string& device);
+    bool IsBootDevice(const Uevent& uevent) const;
 
   private:
     void ColdbootDone() override;