fix various issues

- disable reuse of max_early_data_size.
- make conf_early_data available for server.
- various comment issues

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
index 6640708..e548a21 100644
--- a/include/mbedtls/check_config.h
+++ b/include/mbedtls/check_config.h
@@ -32,7 +32,6 @@
 #error "mbed TLS requires a platform with 8-bit chars"
 #endif
 
-/* Need std integer definition for checking max_early_data_size */
 #include <stdint.h>
 
 #if defined(_WIN32)
@@ -854,9 +853,9 @@
 
 #if defined(MBEDTLS_SSL_EARLY_DATA) && defined(MBEDTLS_SSL_SRV_C) && \
     ( !defined(MBEDTLS_SSL_MAX_EARLY_DATA_SIZE)     || \
-      ( MBEDTLS_SSL_MAX_EARLY_DATA_SIZE <= 0 )      || \
+      ( MBEDTLS_SSL_MAX_EARLY_DATA_SIZE < 0 )       || \
       ( MBEDTLS_SSL_MAX_EARLY_DATA_SIZE > UINT32_MAX ) )
-#error "MBEDTLS_SSL_MAX_EARLY_DATA_SIZE MUST be defined and in range(1..UINT32_MAX)"
+#error "MBEDTLS_SSL_MAX_EARLY_DATA_SIZE MUST be defined and in range(0..UINT32_MAX)"
 #endif
 
 #if defined(MBEDTLS_SSL_PROTO_DTLS)     && \