Changes to allow the entropy tests to work for configurations without an
entropy seed file (MBEDTLS_ENTROPY_NV_SEED), and with no entropy sources
configured (MBEDTLS_TEST_NULL_ENTROPY).
Instead of polling the hardware entropy source a single time and
comparing the output with itself, the source is polled at least twice
and make sure that the separate outputs are different.
The self test is a quick way to check at startup whether the entropy
sources are functioning correctly. The self test only polls 8 bytes
from the default entropy source and performs the following checks:
- The bytes are not all 0x00 or 0xFF.
- The hardware does not return an error when polled.
- The entropy does not provide data in a patter. Only check pattern
at byte, word and long word sizes.
A standard 'test' that writes a seed file is added so that regular tests
still can succeed. This is in lieu of a 'SUITE_PRE_CODE' kind of
arrangement where a suite can run code before (and after) all other code
runs.
A test is added that checks if we can read and write the standard NV
seed file
A test is added that actually checks if the entropy and seed file values
that are the result of just using the NV seed are the same as the manual
calculation.
