x86: i8259: export legacy_pic symbol

The classic PC rtc-coms driver has a workaround for broken ACPI device
nodes for it which lack an irq resource. This workaround used to
unconditionally hardcode the irq to 8 in these cases.

This was causing irq conflict problems on systems without a legacy-pic
so a recent patch added an if (nr_legacy_irqs()) guard to the
workaround to avoid this irq conflict.

nr_legacy_irqs() uses the legacy_pic symbol under the hood causing
an undefined symbol error if the rtc-cmos code is build as a module.

This commit exports the legacy_pic symbol to fix this.

Cc: rtc-linux@googlegroups.com
Cc: alexandre.belloni@free-electrons.com
Signed-off-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>

arch/x86/kernel/i8259.c

@@ -418,6 +418,7 @@ struct legacy_pic default_legacy_pic = {
 };
 
 struct legacy_pic *legacy_pic = &default_legacy_pic;
+EXPORT_SYMBOL(legacy_pic);
 
 static int __init i8259A_init_ops(void)
 {