cros_host: use the platform name to extract the bios image

cros_host.get_platform returns the name to use for extracting the bios
image. Modify servo to try finding an image with this name instead of
only trying to extract the model from the firwmare image.

This will only affect local runs. DUTs in the lab have model and board
saved in the host info store.

BUG=b:171517345
TEST=run provision_FirmwareUpdate on all faft-cr50 duts. Verify all of
them use the same image as before except for sarien. It uses
image-arcada_signed.bin instead of image-arcada.bin.

Change-Id: I4134523fa14953f08c6ecadd5f396694eef6c059
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2495216
Tested-by: Mary Ruthven <mruthven@chromium.org>
Reviewed-by: Brent Peterson <brentpeterson@chromium.org>
Commit-Queue: Mary Ruthven <mruthven@chromium.org>
diff --git a/server/hosts/cros_host.py b/server/hosts/cros_host.py
index 2d26dc5..cfd053d 100644
--- a/server/hosts/cros_host.py
+++ b/server/hosts/cros_host.py
@@ -839,7 +839,7 @@
 
         if model is None or model == '':
             try:
-                model = self.get_platform_from_fwid()
+                model = self.get_platform()
             except Exception as e:
                 logging.warn('Dut is unresponsive: %s', str(e))
 
@@ -869,6 +869,7 @@
             # Extract EC image from tarball
             logging.info('Extracting EC image.')
             ec_image = self.servo.extract_ec_image(board, model, local_tarball)
+            logging.info('Extracted: %s', ec_image)
 
         bios_image = None
         if install_bios:
@@ -876,6 +877,7 @@
             logging.info('Extracting BIOS image.')
             bios_image = self.servo.extract_bios_image(board, model,
                                                        local_tarball)
+            logging.info('Extracted: %s', bios_image)
 
         if not bios_image and not ec_image:
             raise error.TestError('No firmware installation was processed.')