Simplify creation of NativeInputChannel

We don't need to create an object just to pass it to the function.
The target function can do it by itself.
This change will enable opening up
android_view_InputChannel_createInputChannel to the
com_android.._InputManagerService, which will allow the InputManager to
create InputChannel objects.

Bug: 142581626
Test: presubmit
Change-Id: Ide6ba9d88b209f33a0161c61cc49f4e02b8ed486