samples: net: http_client: Update TLS configuration

Python HTTPS server counterpart for the sample now seems to enforce
ECDHE key exchange, so enable it in the sample.

Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>

Author: rlubos

samples/net/sockets/http_client/overlay-tls.conf

@@ -8,6 +8,10 @@ CONFIG_MBEDTLS_BUILTIN=y
 CONFIG_MBEDTLS_ENABLE_HEAP=y
 CONFIG_MBEDTLS_HEAP_SIZE=60000
 CONFIG_MBEDTLS_SSL_MAX_CONTENT_LEN=2048
+CONFIG_MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED=y
+CONFIG_MBEDTLS_ECP_DP_SECP256R1_ENABLED=y
+CONFIG_MBEDTLS_ECDH_C=y
+CONFIG_MBEDTLS_ECP_C=y
 
 CONFIG_NET_SOCKETS_SOCKOPT_TLS=y
 CONFIG_NET_SOCKETS_TLS_MAX_CONTEXTS=6