arm64: Use the new GENERIC_IRQ_MULTI_HANDLER

It appears arm64 copied arm's GENERIC_IRQ_MULTI_HANDLER code, but made
it unconditional.

Converts the arm64 code to use the new generic code, which simply consists
of deleting the arm64 code and setting MULTI_IRQ_HANDLER instead.

Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: linux@armlinux.org.uk
Cc: catalin.marinas@arm.com
Cc: Will Deacon <will.deacon@arm.com>
Cc: jonas@southpole.se
Cc: stefan.kristiansson@saunalahti.fi
Cc: shorne@gmail.com
Cc: jason@lakedaemon.net
Cc: marc.zyngier@arm.com
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: nicolas.pitre@linaro.org
Cc: vladimir.murzin@arm.com
Cc: keescook@chromium.org
Cc: jinb.park7@gmail.com
Cc: yamada.masahiro@socionext.com
Cc: alexandre.belloni@bootlin.com
Cc: pombredanne@nexb.com
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: kstewart@linuxfoundation.org
Cc: jhogan@kernel.org
Cc: mark.rutland@arm.com
Cc: ard.biesheuvel@linaro.org
Cc: james.morse@arm.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: openrisc@lists.librecores.org
Link: https://lkml.kernel.org/r/20180622170126.6308-4-palmer@sifive.com

arch/arm64/Kconfig

@@ -74,6 +74,7 @@ config ARM64
 	select GENERIC_CPU_AUTOPROBE
 	select GENERIC_EARLY_IOREMAP
 	select GENERIC_IDLE_POLL_SETUP
+	select GENERIC_IRQ_MULTI_HANDLER
 	select GENERIC_IRQ_PROBE
 	select GENERIC_IRQ_SHOW
 	select GENERIC_IRQ_SHOW_LEVEL
@@ -264,9 +265,6 @@ config ARCH_SUPPORTS_UPROBES
 config ARCH_PROC_KCORE_TEXT
 	def_bool y
 
-config MULTI_IRQ_HANDLER
-	def_bool y
-
 source "init/Kconfig"
 
 source "kernel/Kconfig.freezer"

arch/arm64/include/asm/irq.h

@@ -8,8 +8,6 @@
 
 struct pt_regs;
 
-extern void set_handle_irq(void (*handle_irq)(struct pt_regs *));
-
 static inline int nr_legacy_irqs(void)
 {
 	return 0;

arch/arm64/kernel/irq.c

@@ -42,16 +42,6 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 	return 0;
 }
 
-void (*handle_arch_irq)(struct pt_regs *) = NULL;
-
-void __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
-{
-	if (handle_arch_irq)
-		return;
-
-	handle_arch_irq = handle_irq;
-}
-
 #ifdef CONFIG_VMAP_STACK
 static void init_irq_stacks(void)
 {