samples: tfm_integration: psa_crypto: improve the MbedTLS configuration

Move supported configuration items from the custom MbedTLS user
configuration file over to the Kconfig overlay.
The correct macros are then defined by the MbedTLS module according
to the values of the Kconfig options.

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