Crypto: Fix Mbed TLS key operation return code

PSA Crypto API spec requests key operation to return error code
PSA_ERROR_INVALID_HANDLE when the key doesn't exist.
However, according to [1], PSA key operation implementation in Mbed TLS
returns PSA_ERROR_DOES_NOT_EXIST instead.

TF-M currently works normally since TF-M specific key handle check will
return PSA_ERROR_INVALID_HANDLE for a non-existing key, without calling
Mbed TLS PSA key operation.

Apply the merged Mbed TLS fix to TF-M to prepare for enhancement of TF-M
key handle check.

[1]: https://github.com/ARMmbed/mbedtls/pull/4198



Change-Id: I79dda1c54dc8377afbfaefdf180bb81c7ff99f02
Signed-off-by: David Hu <david.hu@arm.com>