fancontroller: Add missing config.h

Include config.h to satisfy #ifdef used in those files.

Change-Id: I0f6a3aa750abdf7b7c263d05f0551ee481b98d51
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
diff --git a/pid/fancontroller.cpp b/pid/fancontroller.cpp
index a1290c5..8bbe3f2 100644
--- a/pid/fancontroller.cpp
+++ b/pid/fancontroller.cpp
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "config.h"
+
 #include "fancontroller.hpp"
 
 #include "tuning.hpp"