[Autotest] Tweak touch_UpdateErrors strings.

We want to find kernel errors (like "ERR kernel:") and touch firmware
updater errors (like "NOTICE chromeos-touch-firmware-update[867]:
error:")

We do not want to find random kernel messages like "INFO chrom[23541]:
[...] --enable-touchview [...] --ignore-certificate-errors"

Edit matching strings to filter out "errors" but still pass "err"
and "error"

TEST=ran it
BUG=chromium:558513

Change-Id: I1a1017e6d68c01e041bfefd1db3da67972a4b734
Previous-Reviewed-on: https://chromium-review.googlesource.com/313207
(cherry picked from commit c85038c364ec656cd4245f06e9b99f53ab3e4669)
Reviewed-on: https://chromium-review.googlesource.com/314115
Reviewed-by: Katherine Threlkeld <kathrelkeld@chromium.org>
Commit-Queue: Katherine Threlkeld <kathrelkeld@chromium.org>
Tested-by: Katherine Threlkeld <kathrelkeld@chromium.org>
diff --git a/client/site_tests/touch_UpdateErrors/touch_UpdateErrors.py b/client/site_tests/touch_UpdateErrors/touch_UpdateErrors.py
index 5c4afe1..b22b203 100644
--- a/client/site_tests/touch_UpdateErrors/touch_UpdateErrors.py
+++ b/client/site_tests/touch_UpdateErrors/touch_UpdateErrors.py
@@ -74,7 +74,7 @@
 
         pass_terms = ['touch-firmware-update',
                       '"Product[^a-z0-9]ID[^a-z0-9]*%s"' % hw_id]
-        fail_terms = ['error']
+        fail_terms = ['error[^s]', 'err[^a-z]']
 
         # Check for key terms in touch logs.
         for term in pass_terms + fail_terms: