Fix dependency for TLS 1.3 as well

Turns out TLS 1.3 is using the PK layer for signature generation &
verification, and the PK layer is influenced by USE_PSA_CRYPTO.

Also update docs/use-psa-crypto.md accordingly.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/docs/use-psa-crypto.md b/docs/use-psa-crypto.md
index fc5317a..c63e65a 100644
--- a/docs/use-psa-crypto.md
+++ b/docs/use-psa-crypto.md
@@ -11,12 +11,15 @@
 `psa_crypto_init()` before calling any function from the SSL/TLS, X.509 or PK
 module.
 
-**Scope:** `MBEDTLS_USE_PSA_CRYPTO` has no effect on the parts of the code that
-are specific to TLS 1.3; those parts always use PSA Crypto. The parts of the
-TLS 1.3 code that are common with TLS 1.2, however, follow this option;
-currently this is the record protection code, computation of the running
-handshake hash, and X.509. You need to enable `MBEDTLS_USE_PSA_CRYPTO` if you
-want TLS 1.3 to use PSA everywhere.
+**Scope:** `MBEDTLS_USE_PSA_CRYPTO` has no effect on the most of the TLS 1.3
+code, which always uses PSA crypto. The parts of the TLS 1.3 code that will
+use PSA Crypto or not depending on the value of this option are:
+- record protection;
+- running handshake hash;
+- asymmetric signature verification & generation;
+- X.509 certificate chain verification.
+You need to enable `MBEDTLS_USE_PSA_CRYPTO` if you want TLS 1.3 to use PSA
+everywhere.
 
 New APIs / API extensions
 -------------------------
diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
index 7b1c70c..ca60a9d 100644
--- a/include/mbedtls/check_config.h
+++ b/include/mbedtls/check_config.h
@@ -783,7 +783,7 @@
 
 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED)
 #if !( defined(MBEDTLS_ECDH_C) && defined(MBEDTLS_X509_CRT_PARSE_C) && \
-       ( defined(MBEDTLS_ECDSA_C) || defined(MBEDTLS_PKCS1_V21) ) )
+       ( defined(MBEDTLS_PK_HAVE_ECDSA) || defined(MBEDTLS_PKCS1_V21) ) )
 #error "MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED defined, but not all prerequisites"
 #endif
 #endif