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/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