dts: cpu: add cdns,tensilica-xtensa-lx3

Adds a CPU binding for the Xtensa LX3 core.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>
diff --git a/dts/bindings/cpu/cdns,tensilica-xtensa-lx3.yaml b/dts/bindings/cpu/cdns,tensilica-xtensa-lx3.yaml
new file mode 100644
index 0000000..db17849
--- /dev/null
+++ b/dts/bindings/cpu/cdns,tensilica-xtensa-lx3.yaml
@@ -0,0 +1,8 @@
+# Copyright (c) 2018 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+description: Cadence Tensilica Xtensa LX3 CPU
+
+compatible: "cdns,tensilica-xtensa-lx3"
+
+include: cpu.yaml