[PATCH] ACPI: add missing forward declaration to acpi_bus.h

The header references struct notifier_block but neither includes
linux/notifier.h nor contains the relevant forward declaration. Add the
latter for correctness.

Signed-off-by: Bartosz Golaszewski <[email protected]>
---
 include/acpi/acpi_bus.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index b701b5f972cb..c41d9a7565cf 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -17,6 +17,8 @@
 #include <linux/property.h>
 #include <linux/types.h>
 
+struct notifier_block;
+
 struct acpi_handle_list {
 	u32 count;
 	acpi_handle *handles;
-- 
2.47.3