Set mouse scrolling acceleration to be true by default

By default, the "controlled scrolling" in System > Mouse page should
be false. This requires the default setting value of
isMouseScrollingAccelerationEnabled to be true.

Screenshot:
go/screenshot-brysd8ypt6rpymt

Bug: 30846078
Test: manually verified on test device.
Flag: com.android.hardware.input.mouse_scrolling_acceleration
Change-Id: I6953d94509794e1a480224ae084d9932087fef9c