avr32: remove duplicated #include

Remove duplicated #include in arch/avr32/boards/hammerhead/flash.c.
Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Acked-by: Alex Raimondi <mailinglist@miromico.ch>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>

arch/avr32/boards/hammerhead/flash.c

@@ -15,7 +15,6 @@
 #include <linux/mtd/physmap.h>
 #include <linux/usb/isp116x.h>
 #include <linux/dma-mapping.h>
-#include <linux/platform_device.h>
 #include <linux/delay.h>
 
 #include <mach/portmux.h>