Fixes a regression causing missing scroll events on devices where the
kernel only sets REL_WHEEL/REL_HWHEEL but not the corresponding
hires events. On those devices we would get the legacy axis events but
no longer the new ones.
The mouse wheel plugin will correctly emulate missing hires events
but it doesn't attach to devices where the hires bit is never set.
This plugin can be very simple - since we know we enabled the code on
this device we don't need to keep any extra state around. If our frame
handler is called for this device we want to add the hi-res events.
Theoretically this breaks if the device has only one hi-res axis enabled
but not the other one (i.e. REL_WHEEL_HI_RES but only REL_HWHEEL) but
that's too theoretical to worry about.
Closes#1156
Fixes: 31854a829a ("plugin: only register the wheel plugin on devices that have a wheel")
Part-of: <https://gitlab.freedesktop.org/libinput/libinput/-/merge_requests/1268>
