utils.sh: fetch_file: Use retry option for curl

Retry in case of failure a number of times (5 currently). With the provided
options it should use expontential backoff in case of failures, so should
cover most transient errors, while not spinning retries infinitely.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I66f9cf237897c406ac87f0371cb850e07c28a1dc
1 file changed