headers: kobject.h redux

Remove kobject.h from files which don't need it, notably,
sched.h and fs.h.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h
index 6950c98..78aa104 100644
--- a/include/linux/sunrpc/cache.h
+++ b/include/linux/sunrpc/cache.h
@@ -13,6 +13,7 @@
 #ifndef _LINUX_SUNRPC_CACHE_H_
 #define _LINUX_SUNRPC_CACHE_H_
 
+#include <linux/kref.h>
 #include <linux/slab.h>
 #include <asm/atomic.h>
 #include <linux/proc_fs.h>