rcinput: workaround for VU+ solo2 remote control driver.

The solo2 remote control driver offers all possible
devices (remote control, keyboard, mouse, touchpad)
through one event device node, which confuses enigma,
because enigma assumes that a device that has an 'A'
key, can in fact send that key (and other letters),
while the remote control cannot send letters actually.

This fixes the remote control problems on the VU+ solo,
but it may break non-remote-control devices on this STB.

Also this workaround may or may not be required on
other VU+ STBes.