gtkeventcontrollerscroll: Drop device type checks

gtkeventcontrollerscroll: Drop device type checks

Kinetic scrolling (and begin/end tracking) broke with commit cab1dcb696
since the pointing device used on X11 does not get as much GdkInputSource
granularity as the source device used to have in GTK3.

Actually this is kinda pointless, devices incapable of smooth scroll
should send discrete events, without those devices in the picture, we
want kinetic scroll to apply on every other device capable of smooth
scroll, so just do that.

Fixes: https://gitlab.gnome.org/GNOME/gtk/-/issues/3210