xinput: req ListInputDevices: remove obsolete structs

xinput: req ListInputDevices: remove obsolete structs

Remove structs that are no longer needed because of modeling
this request/reply with new xml-constructs.

Removing these structs modifies the API but maybe it's still OK.

Message-ID: <1409743080-302-7-git-send-email-chris@demorecorder.com>
Patch-Thread-Subject: [Xcb] xinput: make ListInputDevices work, sumof with nested expr, ...
Patch-Set: ListInputDevices
Patch-Number: proto 7/7
Patch-Version: V1
Signed-off-by: Christian Linhart <chris@DemoRecorder.com>