input/synaptics: add tests for scroll buttons
input/synaptics: add tests for scroll buttons

Removed from synaptics 1.7, re-instated later because some fujitsu devices
still ship them.

Signed-off-by: Peter Hutterer <b9c50af7afa7642f6f854434cda9ffe54ece8b85@who-t.net>

freedesktop-unofficial-mirror/xorg__test__xorg-integration-tests,freedesktop-unofficial-mirror/xorg__test__xorg-integration-tests,freedesktop-unofficial-mirror/xorg__test__xorg-integration-tests