x86/ioapic: Change prototype of acpi_ioapic_add()

Change the argument of acpi_ioapic_add() to a generic ACPI handle, and
move its prototype from drivers/acpi/internal.h to include/linux/acpi.h
so that it can be called from outside the pci_root driver.

Signed-off-by: Rui Wang <rui.y.wang@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bhelgaas@google.com
Cc: helgaas@kernel.org
Cc: linux-acpi@vger.kernel.org
Cc: linux-pci@vger.kernel.org
Cc: rjw@rjwysocki.net
Cc: tony.luck@intel.com
Link: http://lkml.kernel.org/r/1471420837-31003-2-git-send-email-rui.y.wang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

include/linux/acpi.h

@@ -751,6 +751,12 @@ static inline int acpi_reconfig_notifier_unregister(struct notifier_block *nb)
 
 #endif	/* !CONFIG_ACPI */
 
+#ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
+int acpi_ioapic_add(acpi_handle root);
+#else
+static inline int acpi_ioapic_add(acpi_handle root) { return 0; }
+#endif
+
 #ifdef CONFIG_ACPI
 void acpi_os_set_prepare_sleep(int (*func)(u8 sleep_state,
 			       u32 pm1a_ctrl,  u32 pm1b_ctrl));