Use Context.getSystemService(Class<T>) for InputManager.

This is a mechanical replacement of Context.getSystemService(String)
with Context.getSystemService(Class<T>) when retrieving InputManager.
Note those are bundled code.  Hence we don't need to make sure
Build.VERSION.SDK_INT >= 23.

Change-Id: Iee47e374e1349720e3100bab33ed139e1f47c169