modules: mbedtls: rename CONFIG_MBEDTLS_MAC_*_ENABLED and rm duplicates

Remove the `_MAC` part because those Kconfig options enable only hash
algorithms, nothing MAC-related, and the `_ENABLED` part to align the
naming to the Mbed TLS defines (plus we don't need such a part).

As a bonus, enabling SHA-256 does not automatically enable SHA-224
anymore.

See the migration guide entries for more details on the practical
changes.

Signed-off-by: Tomi Fontanilles <tomi.fontanilles@nordicsemi.no>