Add reef board to rotating builders.

Add reef board and update caroline description.
Change number of boards tested daily to 3.

BUG=None
Test=3 jobs send to cbuildbot (print only).

Change-Id: I95e7d608b81c5358158c9e8f9d467fbcba74670e
Reviewed-on: https://chromium-review.googlesource.com/490637
Commit-Ready: Manoj Gupta <manojgupta@chromium.org>
Tested-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Luis Lozano <llozano@chromium.org>
diff --git a/buildbot_test_llvm.py b/buildbot_test_llvm.py
index dc0a0ee..527db99 100755
--- a/buildbot_test_llvm.py
+++ b/buildbot_test_llvm.py
@@ -29,7 +29,7 @@
 MAIL_PROGRAM = '~/var/bin/mail-sheriff'
 VALIDATION_RESULT_DIR = os.path.join(CROSTC_ROOT, 'validation_result')
 START_DATE = datetime.date(2016, 1, 1)
-TEST_PER_DAY = 2
+TEST_PER_DAY = 3
 TEST_BOARD = [
     'squawks',  # x86_64, rambi  (baytrail)
     'terra',  # x86_64, strago (braswell)
@@ -41,8 +41,9 @@
     'sentry',  # x86_64, kunimitsu (skylake-u)
     'chell',  # x86_64, glados (skylake-y)
     'daisy',  # arm,    daisy  (exynos)
-    'caroline',  # amd64
+    'caroline',  # x86_64, glados (skylake-y)
     'kevin',  # arm,    gru  (Rockchip)
+    'reef',  # x86_64, reef  (Apollo Lake)
 ]