Remove mosys platform model from GetModelName RPC

We had previously done this in https://crrev.com/c/1925561,
but the CL had to be reverted (https://crrev.com/c/1937666) because it
relied on functionality (cros_config fallbacks) that were not present at
ToT.
That functionality has since been added to Autotest
(https://crrev.com/c/1946703).

BUG=chromium:1023647
TEST=Run firmware_FAFTSetup on both a unibuild board and a non-unibuild
board, with an extra logging line:
logging.info(faft_client.System.GetModelName())

Change-Id: Ibe741faed443db6f6f4d2dfe89495ccb1b320104
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/1986203
Tested-by: Greg Edelston <gredelston@google.com>
Reviewed-by: Kevin Shelton <kmshelton@chromium.org>
Commit-Queue: Greg Edelston <gredelston@google.com>
diff --git a/client/cros/faft/rpc_functions.py b/client/cros/faft/rpc_functions.py
index 0a94efc..34043ec 100644
--- a/client/cros/faft/rpc_functions.py
+++ b/client/cros/faft/rpc_functions.py
@@ -14,6 +14,7 @@
 import traceback
 import xmlrpclib
 
+from autotest_lib.client.common_lib.cros import cros_config
 from autotest_lib.client.cros.faft.utils import (
         cgpt_handler,
         os_interface,
@@ -765,11 +766,11 @@
 
         @return: A string of the model name.
         """
-        lines = self._os_if.run_shell_command_get_output(
-                '(mosys -vvv platform model 2>&1) || echo Failed')
-        if lines[-1].strip() == 'Failed':
-            raise Exception('Failed getting model name: ' + '\n'.join(lines))
-        return lines[-1].strip()
+        model = cros_config.call_cros_config_get_output('/ name',
+                self._os_if.run_shell_command)
+        if not model:
+            raise Exception('Failed getting model name from cros_config')
+        return model
 
     def DevTpmPresent(self):
         """Check if /dev/tpm0 is present.