teensy3: usb_dev: Check wIndex when processing CDC requests

When processing CDC_SET_CONTROL_LINE_STATE and CDC_SET_LINE_CODING
requests, wIndex is ignored.  Hence if the CDC Status Interface is
enabled, these requests are always processed, even when not destined for
the actual serial status interface.

Fix this by adding a check to ensure that wIndex matches the CDC status
interface.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

teensy3/usb_dev.c

 		//serial_print("desc: not found\n");
 		endpoint0_stall();
 		return;
-#if defined(CDC_STATUS_INTERFACE)
 	  case 0x2221: // CDC_SET_CONTROL_LINE_STATE
-		usb_cdc_line_rtsdtr_millis = systick_millis_count;
-		usb_cdc_line_rtsdtr = setup.wValue;
+		switch (setup.wIndex) {
+#ifdef CDC_STATUS_INTERFACE
+		  case CDC_STATUS_INTERFACE:
+			usb_cdc_line_rtsdtr_millis = systick_millis_count;
+			usb_cdc_line_rtsdtr = setup.wValue;
+			break;
+#endif
+		}
 		//serial_print("set control line state\n");
 		break;
+#ifdef CDC_STATUS_INTERFACE
 	  case 0x2321: // CDC_SEND_BREAK
 		break;
 	  case 0x2021: // CDC_SET_LINE_CODING
 	case 0x01:  // OUT transaction received from host
 	case 0x02:
 		//serial_print("PID=OUT\n");
-#ifdef CDC_STATUS_INTERFACE
 		if (setup.wRequestAndType == 0x2021 /*CDC_SET_LINE_CODING*/) {
 			int i;
-			uint8_t *dst = (uint8_t *)usb_cdc_line_coding;
+			uint8_t *dst = NULL;
+			switch (setup.wIndex) {
+#ifdef CDC_STATUS_INTERFACE
+			  case CDC_STATUS_INTERFACE:
+				dst = (uint8_t *)usb_cdc_line_coding;
+				break;
+#endif
+			}
+			if (!dst)
+				break;
+
 			//serial_print("set line coding ");
 			for (i=0; i<7; i++) {
 				//serial_phex(*buf);
 			}
 			//serial_phex32(usb_cdc_line_coding[0]);
 			//serial_print("\n");
-			if (usb_cdc_line_coding[0] == 134) usb_reboot_timer = 15;
+#ifdef CDC_STATUS_INTERFACE
+			if (setup.wIndex == CDC_STATUS_INTERFACE &&
+			    usb_cdc_line_coding[0] == 134)
+				usb_reboot_timer = 15;
+#endif
 			endpoint0_transmit(NULL, 0);
 		}
-#endif
 #ifdef KEYBOARD_INTERFACE
 		if (setup.word1 == 0x02000921 && setup.word2 == ((1<<16)|KEYBOARD_INTERFACE)) {
 			keyboard_leds = buf[0];