init: fix last_reboot_reason string

This got moved when refactoring the reboot commands.

Bug: 37540660
Test: verify bullhead's last_reboot_reason is correct
Change-Id: I3b86496fc469ca41645df7e7ba8bb51dd25b6b38
diff --git a/init/reboot.cpp b/init/reboot.cpp
index 4d65437..a68fd06 100644
--- a/init/reboot.cpp
+++ b/init/reboot.cpp
@@ -429,7 +429,6 @@
 bool HandlePowerctlMessage(const std::string& command) {
     unsigned int cmd = 0;
     std::vector<std::string> cmd_params = android::base::Split(command, ",");
-    std::string reason_string = cmd_params[0];
     std::string reboot_target = "";
     bool run_fsck = false;
     bool command_invalid = false;
@@ -442,7 +441,6 @@
             // The shutdown reason is PowerManager.SHUTDOWN_USER_REQUESTED.
             // Run fsck once the file system is remounted in read-only mode.
             run_fsck = true;
-            reason_string = cmd_params[1];
         }
     } else if (cmd_params[0] == "reboot") {
         cmd = ANDROID_RB_RESTART2;
@@ -473,6 +471,6 @@
         return false;
     }
 
-    DoReboot(cmd, reason_string, reboot_target, run_fsck);
+    DoReboot(cmd, command, reboot_target, run_fsck);
     return true;
 }