fastboot: derive device locked state from Android property

We shall rely on Android property instead of parsing kernel
command line directly: parameters could be originated from
kernel command line or bootconfig.

Bug: 183237066
Bug: 183719613
Signed-off-by: Oleg Matcovschi <omatcovschi@google.com>
Change-Id: Ia70d286646a83a95967ca4293168a6550ffff7f0
diff --git a/fastboot/device/utility.cpp b/fastboot/device/utility.cpp
index f9267e0..07ad902 100644
--- a/fastboot/device/utility.cpp
+++ b/fastboot/device/utility.cpp
@@ -204,12 +204,7 @@
 }
 
 bool GetDeviceLockStatus() {
-    std::string cmdline;
-    // Return lock status true if unable to read kernel command line.
-    if (!android::base::ReadFileToString("/proc/cmdline", &cmdline)) {
-        return true;
-    }
-    return cmdline.find("androidboot.verifiedbootstate=orange") == std::string::npos;
+    return android::base::GetProperty("ro.boot.verifiedbootstate", "") != "orange";
 }
 
 bool UpdateAllPartitionMetadata(FastbootDevice* device, const std::string& super_name,