Remove usage of (fake) Amarok-Mockup theme

This is due to https://bugs.kde.org/show_bug.cgi?id=320855
Amarok-Mockup is unused, as far i can see, and also makes Amarok crash with kdelibs master/4.11
If it is still needed, or there is a better solution, i'll discard the review...

From 6b85a2899a30db5acebee92182a67778499a8d9e Mon Sep 17 00:00:00 2001
From: Hrvoje Senjan <hrvoje.senjan@gmail.com>
Date: Sun, 9 Jun 2013 19:55:58 +0200
Subject: [PATCH 1/1] Kill Amarok-Mockup

BUG: 320855
FIXED-IN: 2.8
REVIEW: 110917