mm/slob: remove CONFIG_SLOB

Remove SLOB from Kconfig and Makefile. Everything under #ifdef
CONFIG_SLOB, and mm/slob.c is now dead code.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
diff --git a/init/Kconfig b/init/Kconfig
index 1fb5f31..72ac3f6 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -973,7 +973,7 @@
 
 config MEMCG_KMEM
 	bool
-	depends on MEMCG && !SLOB
+	depends on MEMCG
 	default y
 
 config BLK_CGROUP