[MIPS] IP27: Don't include <asm/sn/arch.h>.

Nothing <asm/sn/arch.h> defines is used.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

include/asm-mips/mach-ip27/irq.h

@@ -10,8 +10,6 @@
 #ifndef __ASM_MACH_IP27_IRQ_H
 #define __ASM_MACH_IP27_IRQ_H
 
-#include <asm/sn/arch.h>
-
 /*
  * A hardwired interrupt number is completly stupid for this system - a
  * large configuration might have thousands if not tenthousands of