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.cpp b/init/devices.cpp
index f2bb9d2..6a3a64d 100644
--- a/init/devices.cpp
+++ b/init/devices.cpp
@@ -188,6 +188,28 @@
     }
 }
 
+bool DeviceHandler::IsBootDevice(const Uevent& uevent) const {
+    std::string device;
+
+    if (FindPlatformDevice(uevent.path, &device)) {
+        // Skip /devices/platform or /devices/ if present
+        static constexpr std::string_view devices_platform_prefix = "/devices/platform/";
+        static constexpr std::string_view devices_prefix = "/devices/";
+
+        if (StartsWith(device, devices_platform_prefix)) {
+            device = device.substr(devices_platform_prefix.length());
+        } else if (StartsWith(device, devices_prefix)) {
+            device = device.substr(devices_prefix.length());
+        }
+    } else if (FindPciDevicePrefix(uevent.path, &device)) {
+    } else if (FindVbdDevicePrefix(uevent.path, &device)) {
+    } else {
+        return false;
+    }
+
+    return boot_devices_.find(device) != boot_devices_.end();
+}
+
 std::string DeviceHandler::GetPartitionNameForDevice(const std::string& query_device) {
     static const auto partition_map = [] {
         std::vector<std::pair<std::string, std::string>> partition_map;