xinput: struct XIDeviceInfo.name: cleanup of padding

xinput: struct XIDeviceInfo.name: cleanup of padding

Previuosly, the padding of list "name"
has been done by faking another list-length.

Correct this by using the real list-length,
and by adding a 4-byte align-pad after the list.

This yields the same total length of the struct,
and uses the correct length of the list "name".

spec:
http://cgit.freedesktop.org/xorg/proto/inputproto/tree/specs/XI2proto.txt#n768

code:
http://cgit.freedesktop.org/xorg/lib/libXi/tree/src/XIQueryDevice.c#n92
http://cgit.freedesktop.org/xorg/xserver/tree/Xi/xiquerydevice.c#n477