icE1usb fw: Use #define's in descriptors for interface/endpoints ID

This way they can be used in other parts of the code more easily.

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Change-Id: I565d9a43bc26b99bc385b46522e7da6a207b2412
diff --git a/firmware/ice40-riscv/icE1usb/usb_desc_ids.h b/firmware/ice40-riscv/icE1usb/usb_desc_ids.h
new file mode 100644
index 0000000..2247f84
--- /dev/null
+++ b/firmware/ice40-riscv/icE1usb/usb_desc_ids.h
@@ -0,0 +1,17 @@
+/*
+ * usb_desc_ids.h
+ *
+ * Copyright (C) 2022  Sylvain Munaut <tnt@246tNt.com>
+ * SPDX-License-Identifier: LGPL-3.0-or-later
+ */
+
+#pragma once
+
+#define USB_INTF_E1(p)		(0 + (p))
+#define USB_INTF_DFU		1
+#define USB_INTF_NUM		2
+
+#define USB_EP_E1_IN(p)		(0x82 + (3 * (p)))
+#define USB_EP_E1_OUT(p)	(0x01 + (3 * (p)))
+#define USB_EP_E1_FB(p)		(0x81 + (3 * (p)))
+#define USB_EP_E1_INT(p)	(0x83 + (3 * (p)))