ec: Add test to overflow cprints
ec: Add test to overflow cprints

This covers a error handler in cprints that wasn't covered previously.

BRANCH=None
BUG=None
TEST=make test-coverage

Signed-off-by: Jeremy Bettis <4df7b5147fee087dca33c181f288ee7dbf56e022@google.com>
Change-Id: Ibefdeb6f1d83b6822c4251ca8f9108c4377f7442
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3930844
Tested-by: Jeremy Bettis <4df7b5147fee087dca33c181f288ee7dbf56e022@chromium.org>
Auto-Submit: Jeremy Bettis <4df7b5147fee087dca33c181f288ee7dbf56e022@chromium.org>
Reviewed-by: Tristan Honscheid <1e17951ff5ffc8afe254954c03de64afef62fe52@google.com>
Commit-Queue: Jeremy Bettis <4df7b5147fee087dca33c181f288ee7dbf56e022@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec