remove "struct subsystem" as it is no longer needed

We need to work on cleaning up the relationship between kobjects, ksets and
ktypes.  The removal of 'struct subsystem' is the first step of this,
especially as it is not really needed at all.

Thanks to Kay for fixing the bugs in this patch.

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 0d9f984..16c3c44 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -316,7 +316,7 @@
 	u32 data;
 };
 
-extern struct subsystem acpi_subsys;
+extern struct kset acpi_subsys;
 
 /*
  * External Functions