slow-work: kill it

slow-work doesn't have any user left.  Kill it.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: David Howells <dhowells@redhat.com>

init/Kconfig

@@ -1143,30 +1143,6 @@ config TRACEPOINTS
 
 source "arch/Kconfig"
 
-config SLOW_WORK
-	default n
-	bool
-	help
-	  The slow work thread pool provides a number of dynamically allocated
-	  threads that can be used by the kernel to perform operations that
-	  take a relatively long time.
-
-	  An example of this would be CacheFiles doing a path lookup followed
-	  by a series of mkdirs and a create call, all of which have to touch
-	  disk.
-
-	  See Documentation/slow-work.txt.
-
-config SLOW_WORK_DEBUG
-	bool "Slow work debugging through debugfs"
-	default n
-	depends on SLOW_WORK && DEBUG_FS
-	help
-	  Display the contents of the slow work run queue through debugfs,
-	  including items currently executing.
-
-	  See Documentation/slow-work.txt.
-
 endmenu		# General setup
 
 config HAVE_GENERIC_DMA_COHERENT