ARM: at91/at91sam9g45: remove useless header file

Remove this useless cpu.h header file forgotten during the !DT support removal.
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

arch/arm/mach-at91/at91sam9g45.c

@@ -11,7 +11,6 @@
  */
 
 #include <asm/system_misc.h>
-#include <mach/cpu.h>
 #include <mach/hardware.h>
 
 #include "soc.h"