hwcrypto-unittest: Retry RNG Test 3 times

NIST SP 800-22 section 2.13. has exactly 1% chance of failure. This is
not acceptable in CI for actual devices. Retrying 3 times.

Bug: 280985237
Change-Id: I9b291e5784059b7beb9162416355f5e9596c0318
1 file changed