healthd: Remove warning by clang compiler.

Bug: 27265206
Change-Id: I8f2ec1391952de4a9cdefce0433535608a1e9b59
Signed-off-by: Ruchi Kandoi <kandoiruchi@google.com>
diff --git a/healthd/BatteryMonitor.cpp b/healthd/BatteryMonitor.cpp
index 477148b..b33dd28 100644
--- a/healthd/BatteryMonitor.cpp
+++ b/healthd/BatteryMonitor.cpp
@@ -323,11 +323,10 @@
                                 " cc=%d", props.batteryCycleCount);
             }
         } else {
-            snprintf(dmesgline, sizeof(dmesgline),
+            len = snprintf(dmesgline, sizeof(dmesgline),
                  "battery none");
         }
 
-        len = strlen(dmesgline);
         snprintf(dmesgline + len, sizeof(dmesgline) - len, " chg=%s%s%s",
                  props.chargerAcOnline ? "a" : "",
                  props.chargerUsbOnline ? "u" : "",