[crypto] Fix initialization of psa key attributes

[adigie]

psa_key_attributes_t has to be initialized with PSA_KEY_ATTRIBUTES_INIT.

[LuDuda]

@adigie what are the consequences of previous behaviour?

[Damian-Nordic]

This seems unnecessary according to https://arm-software.github.io/psa-api/crypto/1.1/api/keys/attributes.html#c.psa_get_key_attributes

This function first resets the attribute object as with psa_reset_key_attributes(). It then copies the attributes of the given key into the given attribute object.

[adigie]

It freed some random address in the upstream tests on 2.7.0, because of:
https://github.com/nrfconnect/sdk-mbedtls/blob/72868c6f1421afa92cba9f6fe6d1a3f108c174b7/library/psa_crypto_client.c#L19-L19

Now I see that we don't have domain parameters anymore:
https://github.com/nrfconnect/sdk-mbedtls/blob/HEAD/library/psa_crypto_client.c#L19-L19