arm64: Implement arch_irqs_disabled()

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lkml.kernel.org/r/20200821085348.664425120@infradead.org

arch/arm64/include/asm/irqflags.h

@@ -95,6 +95,11 @@ static inline int arch_irqs_disabled_flags(unsigned long flags)
 	return res;
 }
 
+static inline int arch_irqs_disabled(void)
+{
+	return arch_irqs_disabled_flags(arch_local_save_flags());
+}
+
 static inline unsigned long arch_local_irq_save(void)
 {
 	unsigned long flags;