usb: at91_udc: linux/prefetch.h included twice

drivers/usb/gadget/at91_udc.c included 'linux/prefetch.h' twice,
remove the duplicate.
Signed-off-by: Danny Kukawka <danny.kukawka@bisect.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/at91_udc.c

@@ -29,7 +29,6 @@
 #include <linux/clk.h>
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
-#include <linux/prefetch.h>
 
 #include <asm/byteorder.h>
 #include <mach/hardware.h>