MIPS: pistachio: remove obsolete include/asm/mach-pistachio

Since commit 02bd530f ("MIPS: generic: Increase NR_IRQS to 256")
include/asm/mach-pistachio/irq.h just does nothing.
Remove the file along with mach-pistachio folder and include compiler
directive.
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

MAINTAINERS

@@ -14099,7 +14099,6 @@ L:	linux-mips@vger.kernel.org
 S:	Odd Fixes
 F:	arch/mips/boot/dts/img/pistachio*
 F:	arch/mips/configs/pistachio*_defconfig
-F:	arch/mips/include/asm/mach-pistachio/
 F:	arch/mips/pistachio/
 
 PKTCDVD DRIVER

arch/mips/include/asm/mach-pistachio/irq.h

-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * Pistachio IRQ setup
- *
- * Copyright (C) 2014 Google, Inc.
- */
-
-#ifndef __ASM_MACH_PISTACHIO_IRQ_H
-#define __ASM_MACH_PISTACHIO_IRQ_H
-
-#define NR_IRQS 256
-
-#include <asm/mach-generic/irq.h>
-
-#endif /* __ASM_MACH_PISTACHIO_IRQ_H */

arch/mips/pistachio/Platform

 #
 # IMG Pistachio SoC
 #
-cflags-$(CONFIG_MACH_PISTACHIO)		+=				\
-		-I$(srctree)/arch/mips/include/asm/mach-pistachio
 load-$(CONFIG_MACH_PISTACHIO)		+= 0xffffffff80400000
 zload-$(CONFIG_MACH_PISTACHIO)		+= 0xffffffff81000000
 all-$(CONFIG_MACH_PISTACHIO)		:= uImage.gz