buffet: Increase registration timeout

In another buffet CL I increased the delay before buffet will try
to StartDevice. As a result we need to give a larger timeout
window in the tests.

BUG=brillo:451
TEST=test_that <ip> buffet_Registration buffet_BasicDBusAPI

Change-Id: I82d24abfd6be7e1b0df8c878138269ecd15d8123
Reviewed-on: https://chromium-review.googlesource.com/256226
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Commit-Queue: Nathan Bullock <nathanbullock@google.com>
Tested-by: Nathan Bullock <nathanbullock@google.com>
1 file changed