x86: fix sparse warnings in acpi/bus.c

Add function definition and extern variables to asm-x86/acpi.h.

All of these are used in bus.c in ifdef(CONFIG_X86) sections, so are
only added to the x86 include headers. boot.c already includes acpi.h
so no changes are needed there.

Fixes the following:
arch/x86/kernel/acpi/boot.c:83:4: warning: symbol 'acpi_sci_flags' was not declared. Should it be static?
arch/x86/kernel/acpi/boot.c:84:5: warning: symbol 'acpi_sci_override_gsi' was not declared. Should it be static?
arch/x86/kernel/acpi/boot.c:421:13: warning: symbol 'acpi_pic_sci_set_trigger' was not declared. Should it be static?

Signed-off-by: Harvey Harrison <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>

drivers/acpi/bus.c

···
 #include <linux/pm.h>
 #include <linux/device.h>
 #include <linux/proc_fs.h>
+#include <linux/acpi.h>
 #ifdef CONFIG_X86
 #include <asm/mpspec.h>
 #endif
···
 
 #define _COMPONENT		ACPI_BUS_COMPONENT
 ACPI_MODULE_NAME("bus");
-#ifdef	CONFIG_X86
-extern void __init acpi_pic_sci_set_trigger(unsigned int irq, u16 trigger);
-#endif
 
 struct acpi_device *acpi_root;
 struct proc_dir_entry *acpi_root_dir;
···
 
 #ifdef CONFIG_X86
 	if (!acpi_ioapic) {
-		extern u8 acpi_sci_flags;
-
 		/* compatible (0) means level (3) */
 		if (!(acpi_sci_flags & ACPI_MADT_TRIGGER_MASK)) {
 			acpi_sci_flags &= ~ACPI_MADT_TRIGGER_MASK;
···
 		acpi_pic_sci_set_trigger(acpi_gbl_FADT.sci_interrupt,
 					 (acpi_sci_flags & ACPI_MADT_TRIGGER_MASK) >> 2);
 	} else {
-		extern int acpi_sci_override_gsi;
 		/*
 		 * now that acpi_gbl_FADT is initialized,
 		 * update it with result from INT_SRC_OVR parsing

include/asm-x86/acpi.h

···
 extern int acpi_skip_timer_override;
 extern int acpi_use_timer_override;
 
+extern u8 acpi_sci_flags;
+extern int acpi_sci_override_gsi;
+void acpi_pic_sci_set_trigger(unsigned int, u16);
+
 static inline void disable_acpi(void)
 {
 	acpi_disabled = 1;