fixed icon names

kcm/kcm_fancontrol.desktop

@@ -1,6 +1,6 @@
 [Desktop Entry]
 Exec=kcmshell5 kcm_fancontrol
-Icon=fancontrol-gui
+Icon=fancontrol_gui
 Type=Service
  
 X-KDE-ServiceTypes=KCModule

package/metadata.desktop

@@ -1,7 +1,7 @@
 [Desktop Entry]
 Name=Fancontrol-GUI-QML-Package
 Comment=Control PWM-fans
-Icon=fancontrol-gui
+Icon=fancontrol_gui
 Encoding=UTF-8
 Keywords=
 Type=Service