x86/apic: Make init_legacy_irqs() __init

This function is only called by arch_early_irq_init(), which is an
__init function, so mark the child function __init as well.

In addition mark it inline for the !CONFIG_X86_IO_APIC case.
Signed-off-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1498040061-5332-1-git-send-email-douly.fnst@cn.fujitsu.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/apic/vector.c

@@ -405,7 +405,7 @@ int __init arch_probe_nr_irqs(void)
 }
 
 #ifdef	CONFIG_X86_IO_APIC
-static void init_legacy_irqs(void)
+static void __init init_legacy_irqs(void)
 {
 	int i, node = cpu_to_node(0);
 	struct apic_chip_data *data;
@@ -424,7 +424,7 @@ static void init_legacy_irqs(void)
 	}
 }
 #else
-static void init_legacy_irqs(void) { }
+static inline void init_legacy_irqs(void) { }
 #endif
 
 int __init arch_early_irq_init(void)