bblayers.conf.sample: Add Linaro's OP-TEE repo

OP-TEE recipes are taken from Linaro repo.

Signed-off-by: Santeri Salko <santeri.salko@huawei.com>

flavours/linux/bblayers.conf.sample

@@ -35,4 +35,5 @@ BBLAYERS ?= " \
   ##OEROOT##/../meta-homeassistant \
   ##OEROOT##/../meta-raspberrypi \
   ##OEROOT##/../meta-security \
+  ##OEROOT##/../meta-linaro/meta-optee \
   "