TouchInputMapper: remove UNSCALED mode

This was only used for captured touchpads, which are now handled by
TouchpadInputMapper and its CapturedTouchpadEventConverter, so we can
remove it.

It seems that previously UNSCALED mode was (intentionally or not) being
used by configureInputDevice as a sort of fallback, if the device didn't
match any of the other valid configurations (e.g. if it had
DeviceType::TOUCH_SCREEN but no associated display). It wouldn't have
done much good even if it was intentional, so in those cases log a
warning and set the device to disabled.

Bug: 281840344
Test: atest inputflinger_tests
Test: capture a touchpad using a test app and check it works
Change-Id: I5a8e7c181fd984fa9595c5e232fb913d020dad70