[autotest] Flash EC according to the chip name

The flash_ec doesn't keep all the board variants and doesn't know how
to program in some boards. Should call the flash_ec by passing the
chip name instead of the board name.

CQ-DEPEND=CL:287445,CL:287600
BUG=chromium:505003
TEST=Ran the following Python code to test:
> import common
> from autotest_lib.server.hosts import servo_host
> sh = servo_host.create_servo_host(DUT_IP_ADDRESS, {})
> sh._servo.program_ec(EC_IMAGE_PATH)

Change-Id: I82e9e2cc5c4ab6fd4d7eef0a977f665bc8b4f842
Reviewed-on: https://chromium-review.googlesource.com/287601
Trybot-Ready: Wai-Hong Tam <waihong@chromium.org>
Tested-by: Wai-Hong Tam <waihong@chromium.org>
Reviewed-by: Dan Shi <dshi@chromium.org>
Commit-Queue: Wai-Hong Tam <waihong@chromium.org>
diff --git a/server/cros/servo/firmware_programmer.py b/server/cros/servo/firmware_programmer.py
index 29d9a83..6f79253 100644
--- a/server/cros/servo/firmware_programmer.py
+++ b/server/cros/servo/firmware_programmer.py
@@ -190,16 +190,14 @@
         self._servo = servo
 
 
-    def prepare_programmer(self, image, board=None):
+    def prepare_programmer(self, image):
         """Prepare programmer for programming.
 
         @param image: string with the location of the image file
-        @param board: Name of the board used in EC image. Some board's name used
-                      by servod might be different from EC. Default to None.
         """
         # TODO: need to not have port be hardcoded
-        self._program_cmd = ('flash_ec --board=%s --image=%s --port=%s' %
-                             (board or self._servo.get_board(), image, '9999'))
+        self._program_cmd = ('flash_ec --chip=%s --image=%s --port=%s' %
+                             (self._servo.get('ec_chip'), image, '9999'))
 
 
 class ProgrammerV2(object):
@@ -360,13 +358,11 @@
         self._bios_programmer.program()
 
 
-    def program_ec(self, image, board=None):
+    def program_ec(self, image):
         """Programs the DUT with provide ec image.
 
         @param image: (required) location of ec image file.
-        @param board: Name of the board used in EC image. Some board's name used
-                      by servod might be different from EC. Default to None.
 
         """
-        self._ec_programmer.prepare_programmer(image, board)
+        self._ec_programmer.prepare_programmer(image)
         self._ec_programmer.program()