usb_cdc: Allow USB endpoint ids to be board specific

It's common for boards to have restrictions on the type of each
endpoint.  So, make it possible for the board to select the endpoint
ids for each endpoint.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/generic/usb_cdc.c

@@ -6,12 +6,13 @@
 
 #include <string.h> // memmove
 #include "board/pgm.h" // PROGMEM
-#include "board/usb_cdc.h" // usb_notify_setup
+#include "board/usb_cdc_ep.h" // USB_CDC_EP_BULK_IN
 #include "byteorder.h" // cpu_to_le16
 #include "command.h" // output
 #include "generic/usbstd.h" // struct usb_device_descriptor
 #include "generic/usbstd_cdc.h" // struct usb_cdc_header_descriptor
 #include "sched.h" // sched_wake_task
+#include "usb_cdc.h" // usb_notify_setup
 
 // XXX - move to Kconfig
 #define CONFIG_USB_VENDOR_ID 0x2341