modules: mbedtls: remove the default enabling of features

In an effort to shave off code size, remove out-of-the-box
enabling of crypto features (except SHA-256).

Configurations are adjusted to enable what they need.

Bonuses:

- When enabled, AES now defaults to using a smaller version
(`CONFIG_MBEDTLS_AES_ROM_TABLES` isn't default enabled anymore,
and if enabled, `CONFIG_MBEDTLS_AES_FEWER_TABLES` defaults to y).

- Conditions around Mbed TLS Kconfig options have been improved
to reflect the reality of the dependencies.

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