Implement support for MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS

According to the design in psa-driver-interface.md. Compiles without
issue in test_psa_crypto_drivers.

Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
diff --git a/library/version_features.c b/library/version_features.c
index 9332987..f665a23 100644
--- a/library/version_features.c
+++ b/library/version_features.c
@@ -438,6 +438,9 @@
 #if defined(MBEDTLS_PKCS1_V21)
     "MBEDTLS_PKCS1_V21",
 #endif /* MBEDTLS_PKCS1_V21 */
+#if defined(MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS)
+    "MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS",
+#endif /* MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS */
 #if defined(MBEDTLS_PSA_CRYPTO_CLIENT)
     "MBEDTLS_PSA_CRYPTO_CLIENT",
 #endif /* MBEDTLS_PSA_CRYPTO_CLIENT */