atusb/fw/: remove unused items when building the USB driver for the boot loader

- usb/atu2.c (NUM_EPS), board.h (NUM_EPS): moved definition to
  board.h
- board.h (NUM_EPS): use one EP for the boot loader, two for the
  application
- usb/atu2.c (ep_init): initialize EP 1 only in an application build

atusb/fw/board.h

@@ -64,6 +64,12 @@
 
 #define	BOARD_MAX_mA	40
 
+#ifdef BOOT_LOADER
+#define	NUM_EPS	1
+#else
+#define	NUM_EPS	2
+#endif
+
 #define	HAS_BOARD_SERNUM
 
 extern uint8_t board_sernum[42];

atusb/fw/usb/atu2.c

@@ -40,9 +40,6 @@
 #endif
 
 
-#define NUM_EPS	2
-
-
 struct ep_descr eps[NUM_EPS];
 
 
@@ -199,6 +196,8 @@ static void ep_init(void)
 	eps[0].state = EP_IDLE;
 	eps[0].size = 64;
 
+#ifndef BOOT_LOADER
+
 	UENUM = 1;
 	UECONX = (1 << RSTDT) | (1 << EPEN);	/* enable */
 	UECFG0X = (1 << EPTYPE1) | (1 << EPDIR); /* bulk IN */
@@ -211,6 +210,8 @@ static void ep_init(void)
 
 	eps[1].state = EP_IDLE;
 	eps[1].size = 64;
+
+#endif
 }