[build] Fix "implicit declaration of function" compilation warning

usb_moded_send_whitelisted_modes_signal() function is used without
including the header where the function is declared - which then
leads to compilation time warnings.

Fix the issue by adding the required #include statements.

Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

src/usb_moded-config.c

@@ -42,6 +42,8 @@
 #include "usb_moded-log.h"
 #include "usb_moded-modes.h"
 #include "usb_moded-modesetting.h"
+#include "usb_moded-dbus.h"
+#include "usb_moded-dbus-private.h"
 
 #ifdef USE_MER_SSU
 # include "usb_moded-ssu.h"