ast2600: Add IMA/EVM config variables to local.conf

IMA and EVM support requires Linux kernel support that can be enabled with
the DISTRO_FEATURE 'ima'. Add this to local.conf.

Beyond that, IMA and EVM require a couple of variables that the user should
set for her own needs, such as keys and certs used by IMA.

Have executables in the filesystem signed by inheriting the ima-evm-rootfs
IMAGE_CLASS.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
diff --git a/meta-evb/meta-evb-aspeed/meta-evb-ast2600/conf/templates/default/bblayers.conf.sample b/meta-evb/meta-evb-aspeed/meta-evb-ast2600/conf/templates/default/bblayers.conf.sample
index 04e4ebb..321d05e 100644
--- a/meta-evb/meta-evb-aspeed/meta-evb-ast2600/conf/templates/default/bblayers.conf.sample
+++ b/meta-evb/meta-evb-aspeed/meta-evb-ast2600/conf/templates/default/bblayers.conf.sample
@@ -14,4 +14,5 @@
   ##OEROOT##/meta-phosphor \
   ##OEROOT##/meta-aspeed \
   ##OEROOT##/meta-evb/meta-evb-aspeed/meta-evb-ast2600 \
+  ##OEROOT##/meta-security/meta-integrity \
   "