charger: launch charger using /charger symlink

This makes it consistent with all other targets, especially since
the /sbin/healthd is renamed and likely going away.

Update the seclable accordingly too

Test: Tested charging only mode

Change-Id: Id25f38662b9e8b4eb3ded70a382f2f4e4c972a30
Signed-off-by: Sandeep Patil <sspatil@google.com>
diff --git a/init.bullhead.rc b/init.bullhead.rc
index 2250ed1..61fd977 100644
--- a/init.bullhead.rc
+++ b/init.bullhead.rc
@@ -363,10 +363,10 @@
     user root
     group root
 
-service charger /sbin/healthd -c
+service charger /charger
     class charger
     critical
-    seclabel u:r:healthd:s0
+    seclabel u:r:charger:s0
 
 service qcamerasvr /vendor/bin/mm-qcamera-daemon
     class late_start