uterm_input: remove supporting code for updating LED state

uterm_input: remove supporting code for updating LED state

Before we transitioned to xkbcommon, we had some code that, upon
returning from a VT-switch, looked at the evdev led state and updated
the keyboard modifier state accordingly. So if we returned and NumLock
was on, we adjusted ourselves to that. That was pretty cute.

xkbcommon however doesn't support updating the state by LEDs like that.
Normally, the state of the LEDs is derived from the modifiers; going the
other way is tricky, error-prone and not used much. What we should be
doing is updating the LEDs according to *our* state.

This commit does the part of removing the unused dead code.

Signed-off-by: Ran Benita <ran234@gmail.com>
Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>