Fix .desktop file to adhere to modern FDO standards.

--- a/thinkhdaps.desktop
+++ b/thinkhdaps.desktop
@@ -2,6 +2,6 @@
 Name=ThinkHDAPS
 Comment=Monitor your HDAPS-enabled harddisk
 Exec=thinkhdaps
-Icon=thinkhdaps-logo.svg
+Icon=thinkhdaps-logo
 Type=Application
 Categories=System