ACPI: fix acpi_debugfs_init prototype

acpi_debugfs_init function is declared with return type int in
drivers/acpi/internal.h when CONFIG_DEBUG_FS is enabled, but its
definition in drivers/acpi/debugfs.c has return type void. This is due
to commit aecad432fd68 ("ACPI: Cleanup custom_method debug stuff"),
which changed the return type from int to void without updating the
declaration.

Fix this inconsistency by updating acpi_debugfs_init prototype. While
at it, include internal.h in debugfs.c so that the compiler can check
that the declaration and definition remain compatible.

Signed-off-by: Nicolas Iooss <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>

drivers/acpi/debugfs.c

···
 #include <linux/debugfs.h>
 #include <linux/acpi.h>
 
+#include "internal.h"
+
 #define _COMPONENT		ACPI_SYSTEM_COMPONENT
 ACPI_MODULE_NAME("debugfs");
 

drivers/acpi/internal.h

···
 
 #ifdef CONFIG_DEBUG_FS
 extern struct dentry *acpi_debugfs_dir;
-int acpi_debugfs_init(void);
+void acpi_debugfs_init(void);
 #else
 static inline void acpi_debugfs_init(void) { return; }
 #endif