hdctools: Add overlay for sarien board

Add a simple overlay for the sarien board.

Turn off JTAG vref sel0/sel1 and UART1_EN so the EC can power
up from G3.

BUG=b:117346725
TEST=sudo servod -b sarien, apply power to sarien board and see it boot

Change-Id: Ib3850ac93cd1bf37577ff420102d2b29b578c999
Signed-off-by: Duncan Laurie <dlaurie@google.com>
Reviewed-on: https://chromium-review.googlesource.com/1266022
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Lijian Zhao <lijian.zhao@intel.com>
diff --git a/servo/data/servo_sarien_overlay.xml b/servo/data/servo_sarien_overlay.xml
new file mode 100644
index 0000000..9c7a56b
--- /dev/null
+++ b/servo/data/servo_sarien_overlay.xml
@@ -0,0 +1,29 @@
+<root>
+  <!-- ******** Includes ******** -->
+  <include>
+    <name>servoflex_v2_r0_p50.xml</name>
+  </include>
+  <include>
+    <name>cr50.xml</name>
+  </include>
+  <!-- ******** Controls ******** -->
+  <control>
+    <name>fw_wp_state</name>
+    <doc>Used to turn fw wp off and on</doc>
+    <params clobber_ok="" fw_wp_vref="pp3300"/>
+  </control>
+  <!-- cr50 UART Buffers & VREF Controls -->
+  <control>
+    <name>jtag_vref_sel0</name>
+    <params clobber_ok="" init="off"></params>
+  </control>
+  <control>
+    <name>jtag_vref_sel1</name>
+    <params clobber_ok="" init="off"></params>
+  </control>
+  <control>
+    <name>uart1_en</name>
+    <alias>ec_uart_en</alias>
+    <params clobber_ok="" init="off"></params>
+  </control>
+</root>
diff --git a/servo/servo_interfaces.py b/servo/servo_interfaces.py
index 78d9177..5030ac5 100644
--- a/servo/servo_interfaces.py
+++ b/servo/servo_interfaces.py
@@ -269,6 +269,7 @@
     'poppy',
     'rammus',
     'reef',
+    'sarien',
     'scarlet',
     'sentry',
     'soraka',