kbuild: remove obj-n and lib-n handling

Kconfig never defines CONFIG_* as 'n'.
Now obj-n is only used in firmware/Makefile and it can be
replaced with obj-.  No makefile uses lib-n.

Let's rip off obj-n and lib-n.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Peter Foley <pefoley2@pefoley.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 5b09d36..649ce68 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -79,11 +79,11 @@
 
 # ===========================================================================
 
-ifneq ($(strip $(lib-y) $(lib-m) $(lib-n) $(lib-)),)
+ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
 lib-target := $(obj)/lib.a
 endif
 
-ifneq ($(strip $(obj-y) $(obj-m) $(obj-n) $(obj-) $(subdir-m) $(lib-target)),)
+ifneq ($(strip $(obj-y) $(obj-m) $(obj-) $(subdir-m) $(lib-target)),)
 builtin-target := $(obj)/built-in.o
 endif