added dcd_sof_enable() stubs for all other ports

src/portable/nuvoton/nuc120/dcd_nuc120.c

@@ -497,4 +497,12 @@ void dcd_connect(uint8_t rhport)
   usb_attach();
 }
 
+void dcd_sof_enable(uint8_t rhport, bool en)
+{
+  (void) rhport;
+  (void) en;
+
+  // TODO implement later
+}
+
 #endif

src/portable/nuvoton/nuc121/dcd_nuc121.c

@@ -551,4 +551,12 @@ void dcd_connect(uint8_t rhport)
   usb_attach();
 }
 
+void dcd_sof_enable(uint8_t rhport, bool en)
+{
+  (void) rhport;
+  (void) en;
+
+  // TODO implement later
+}
+
 #endif

src/portable/nuvoton/nuc505/dcd_nuc505.c

@@ -720,4 +720,12 @@ void dcd_connect(uint8_t rhport)
   usb_attach();
 }
 
+void dcd_sof_enable(uint8_t rhport, bool en)
+{
+  (void) rhport;
+  (void) en;
+
+  // TODO implement later
+}
+
 #endif