This patch adds support for the ET&T TC4UM 4-wire USB touchscreen
controller and tries to reuse the bits for TC5UH controller in kernel
already. Data interface is same.
Tested-by: Roger Pueyo Centelles <rogerpueyo@rogerpueyo.com> Signed-off-by: Petr Štetiar <ynezz@true.cz> Signed-off-by: Dmitry Torokhov <dtor@mail.ru>