lookandfeel kcm: Simplify CMake if condition

kcms/lookandfeel/CMakeLists.txt

@@ -5,14 +5,8 @@ if(X11_Xcursor_FOUND)
     set(HAVE_XCURSOR TRUE)
 endif()
 
-if(${Breeze_FOUND})
-    if(${BREEZE_WITH_KDECORATION})
-        set(HAVE_BREEZE_DECO true)
-    else()
-        set(HAVE_BREEZE_DECO FALSE)
-    endif()
-else()
-    set(HAVE_BREEZE_DECO FALSE)
+if(${Breeze_FOUND} AND ${BREEZE_WITH_KDECORATION})
+    set(HAVE_BREEZE_DECO TRUE)
 endif()
 
 configure_file (config-kcm.h.cmake ${CMAKE_CURRENT_BINARY_DIR}/config-kcm.h )