Use P400 NVIDIA GPUs for Windows GPU perf bots.

The new cards were replaced in the old machines already, this change
should get the tests running again with upgraded hardware.

BUG=780296
NOTRY=true

Change-Id: I4cffcee857e80c6e6742e2c507aa971a7b0bdd26
Reviewed-on: https://chromium-review.googlesource.com/747942
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#512986}

tools/perf/core/perf_data_generator.py

@@ -443,7 +443,7 @@ def get_waterfall_config():
     'chromium-rel-win7-gpu-nvidia', 'win',
     swarming=[
       {
-       'gpu': '10de:104a',
+       'gpu': '10de:1cb3',
        'os': 'Windows-2008ServerR2-SP1',
        'pool': 'Chrome-perf',
        'device_ids': [