firmware: change firmware_kset to firmware_kobj

There is no firmware "subsystem" it's just a directory in /sys that
other portions of the kernel want to hook into.  So make it a kobject
not a kset to help alivate anyone who tries to do some odd kset-like
things with this.

Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index e550da6..1b4cf98 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -755,7 +755,7 @@
 		return -ENODEV;
 	}
 
-	acpi_kobj = kobject_create_and_add("acpi", &firmware_kset->kobj);
+	acpi_kobj = kobject_create_and_add("acpi", firmware_kobj);
 	if (!acpi_kobj) {
 		printk(KERN_WARNING "%s: kset create error\n", __FUNCTION__);
 		acpi_kobj = NULL;