DeviceStateMonitor#setAlwaysReportSignalStrength does not work

When constructing the msg, the isEnable info is stored in
msg.obj (when call #obtainMessage with two parameters, the second
parameter is msg.obj instead of msg.arg1). While all msg
handler will take the info from msg.arg1 instead, this info
will get lost when deliver to handler.

The issue is fixed by storing the isEnable info in msg.arg1.

Bug: 178724716
Test: atest com.android.internal.telephony.DeviceStateMonitorTest
Change-Id: I8e755a07b9e58b18693f34fecb3e1e17af696bd9