Drop unused KF5Plasma dependency

This had been already dropped in commit 1d60f46f, which was reverted in
commit 8ba8a29c

. At least that part of it was correct though.
Signed-off-by: Andreas Sturmlechner <asturm@gentoo.org>

CMakeLists.txt

@@ -32,7 +32,6 @@ find_package(KF5 ${KF5_MIN_VERSION} REQUIRED COMPONENTS
     KDELibs4Support
     DBusAddons
     KCMUtils
-    Plasma
 )
 
 find_package(X11 REQUIRED OPTIONAL_COMPONENTS Xtst)