usb.h: use standard __LITTLE_ENDIAN from Linux headers

Rather than forcing people to define a custom "LITTLEENDIAN", just use the
__LITTLE_ENDIAN one from the Linux byteorder headers that every arch is
already setting up.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Remy Bohmer <linux@bohmer.net>
diff --git a/cpu/arm920t/s3c24x0/usb_ohci.c b/cpu/arm920t/s3c24x0/usb_ohci.c
index 641f270..9cbd477 100644
--- a/cpu/arm920t/s3c24x0/usb_ohci.c
+++ b/cpu/arm920t/s3c24x0/usb_ohci.c
@@ -29,9 +29,7 @@
  */
 /*
  * IMPORTANT NOTES
- * 1 - you MUST define LITTLEENDIAN in the configuration file for the
- *     board or this driver will NOT work!
- * 2 - this driver is intended for use with USB Mass Storage Devices
+ * 1 - this driver is intended for use with USB Mass Storage Devices
  *     (BBB) ONLY. There is NO support for Interrupt or Isochronous pipes!
  */