Update to accomodate for new tree layout

user-task.mk should be referred relative to top of the tree
as trusty/kernel/app/trusty/user-task.mk

Bug: 111521896
Change-Id: I500ae90ed963f0ab2c62c4385a44c9fc65a02b26
diff --git a/project/imx6ul-inc.mk b/project/imx6ul-inc.mk
index 9629742..c0c0b41 100644
--- a/project/imx6ul-inc.mk
+++ b/project/imx6ul-inc.mk
@@ -77,4 +77,4 @@
 # This project requires trusty IPC
 WITH_TRUSTY_IPC := true
 
-EXTRA_BUILDRULES += app/trusty/user-tasks.mk
+EXTRA_BUILDRULES += trusty/kernel/app/trusty/user-tasks.mk