Remove code that fixed YCP module names

It turned out that original (unfixed) module names also appeared in
other contexts than <block type="module">, e.g. when calling a module's
function. Rather than fix all the occurences, we decided to make all
module names in upstream valid Ruby class names.

This commit removes the fixup code and restores a check that was removed
in 820200fa2476353bcc8de835b547b756adb9368c.