security: cleanup Makefiles to use standard syntax for specifying sub-directories

The Makefiles in security/ uses a non-standard way to
specify sub-directories for building.

Fix it up so the normal (and documented) approach is used.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: James Morris <james.l.morris@oracle.com>
diff --git a/security/integrity/Makefile b/security/integrity/Makefile
index 0f9cffb..0793f48 100644
--- a/security/integrity/Makefile
+++ b/security/integrity/Makefile
@@ -10,6 +10,6 @@
 integrity-y := iint.o
 
 subdir-$(CONFIG_IMA)			+= ima
-obj-$(CONFIG_IMA)			+= ima/built-in.o
+obj-$(CONFIG_IMA)			+= ima/
 subdir-$(CONFIG_EVM)			+= evm
-obj-$(CONFIG_EVM)			+= evm/built-in.o
+obj-$(CONFIG_EVM)			+= evm/