Add feature support for DES for PSA crypto config

Basic support for enabling DES through PSA_WANT_KEY_TYPE_DES.

Signed-off-by: David Brown <david.brown@linaro.org>
diff --git a/include/mbedtls/config_psa.h b/include/mbedtls/config_psa.h
index a4b4f91..e80a8e6 100644
--- a/include/mbedtls/config_psa.h
+++ b/include/mbedtls/config_psa.h
@@ -238,6 +238,12 @@
 #endif /*!MBEDTLS_PSA_ACCEL_KEY_TYPE_CAMELLIA */
 #endif /* PSA_WANT_KEY_TYPE_CAMELLIA */
 
+#if defined(PSA_WANT_KEY_TYPE_DES)
+#if !defined(MBEDTLS_PSA_ACCEL_KEY_TYPE_DES)
+#define MBEDTLS_DES_C
+#endif /*!MBEDTLS_PSA_ACCEL_KEY_TYPE_DES */
+#endif /* PSA_WANT_KEY_TYPE_DES */
+
 #else /* MBEDTLS_PSA_CRYPTO_CONFIG */
 
 /*
@@ -358,6 +364,10 @@
 #define PSA_WANT_KEY_TYPE_CAMELLIA 1
 #endif
 
+#if defined(MBEDTLS_DES_C)
+#define PSA_WANT_KEY_TYPE_DES 1
+#endif
+
 #endif /* MBEDTLS_PSA_CRYPTO_CONFIG */
 
 #ifdef __cplusplus