Point to linaro-swg/linux.git branch optee

Instead of using a fixed commit for Linux, track the tip of the "optee"
Linaro branch, like we do for other Linaro Gits (optee_*).

Signed-off-by: Jerome Forissier <jerome@forissier.org>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
Reviewed-by: Joakim Bech <joakim.bech@linaro.org>
Change-Id: Ie72b1c0def38b378fa411370492ffed2bfd96376
diff --git a/hikey.xml b/hikey.xml
index 1a11a6b..2afe1ff 100644
--- a/hikey.xml
+++ b/hikey.xml
@@ -15,7 +15,7 @@
         </project>
 
         <!-- linaro-swg gits -->
-        <project path="linux"                name="linaro-swg/linux.git"                  revision="1ad01d3482219ee7fcc5a4529f8f06570878bf72" />
+        <project path="linux"                name="linaro-swg/linux.git"                  revision="optee" clone-depth="1" />
         <project path="optee_examples"       name="linaro-swg/optee_examples.git" />
         <project path="patches_hikey"        name="linaro-swg/patches_hikey.git"          revision="d9c07f0ac0ce5fe57d367be82b8673aae8e81e96" />