
Smaller implementation for SHA256 and SHA512 helps to reduce the ROM footprint though it has a certain impact on performance. As a trade-off, enable it as a default config when MbedTLS is enabled can reduce the target size significantly with acceptable performance loss. Signed-off-by: Raymond Mao <raymond.mao@linaro.org> Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>