ARM: at91: remove useless header file includes

Since removal of !DT boards, asm/irq.h inclusion is not needed in these product
files.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
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 <asm/irq.h>
 #include <mach/hardware.h>
 
 #include "soc.h"

arch/arm/mach-at91/at91sam9rl.c

@@ -10,7 +10,6 @@
  */
 
 #include <asm/system_misc.h>
-#include <asm/irq.h>
 #include <mach/cpu.h>
 #include <mach/at91_dbgu.h>
 #include <mach/hardware.h>