Re-restore mbedtls_x509_string_to_names() to public as our example
programs use it, and it is the reverse of mbedtls_x509_dn_gets().
Add a docstring, so that it is a properly documented public function.
Signed-off-by: David Horstmann <david.horstmann@arm.com>
This function should be internal, being exposed only via functions like
mbedtls_x509write_crt_set_subject_name().
Signed-off-by: David Horstmann <david.horstmann@arm.com>
