mbedtls: add Kconfig option for PSA_WANT_ALG_SHA_256

Create a new Kconfig named CONFIG_PSA_WANT_ALG_SHA_256 which allows to
enable PSA_WANT_ALG_SHA_256. This allows to use PSA functions to
compute SHA256 hashes. When PSA is provided by TFM this allows also
to remove legacy mbedtls_sha256() support and therefore reduce
footprint for the NS side.

Signed-off-by: Valerio Setti <vsetti@baylibre.com>
3 files changed