[libcalamaresui] Remove the signal done() from ViewStep

- The signal is emitted, generally from next(), but not actually used.

src/modules/keyboard/KeyboardViewStep.cpp

@@ -68,8 +68,6 @@ KeyboardViewStep::widget()
 void
 KeyboardViewStep::next()
 {
-    //TODO: actually save those settings somewhere
-    emit done();
 }