Adding stepcounter and stepdetector xml files to device.mk.
Adding stepcounter and stepdetector xml files to device.mk.

Change-Id: I6c7620d121943a24a937635f8c7d63044a682740

maruos/android_device_lge_hammerhead,maruos/android_device_lge_hammerhead,maruos/android_device_lge_hammerhead,maruos/android_device_lge_hammerhead