Add mb_config for chromeos-kevin-chrome

R=bpastene@google.com

Bug: 988587
Change-Id: Ibb108af5589365d74f00572799e10ea7ed227863
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1749959Reviewed-by: Ben Pastene <bpastene@chromium.org>
Commit-Queue: Anushruth  <anushruth@chromium.org>
Cr-Commit-Position: refs/heads/master@{#686274}

tools/mb/mb_config.pyl

@@ -698,6 +698,7 @@
 
     'tryserver.chrome': {
       'chromeos-betty-chrome': 'official_cros_chrome_sdk_headless_ozone',
+      'chromeos-kevin-chrome': 'official_cros_chrome_sdk_headless_ozone',
       'linux-chrome': 'official_goma',
       'linux-chromeos-chrome': 'official_goma_chromeos_minimal_symbols',
       'win_chrome_official': 'official_goma_x86',