Revert "Removed the unused port_api.c driver code."

This reverts commit 9fad25f.

Author: andrewc-arm

targets/TARGET_Samsung/TARGET_SIDK_S5JS100/port_api.c

@@ -0,0 +1,74 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2018 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/****************************************************************************
+ *
+ * Copyright 2019 Samsung Electronics All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
+ * either express or implied. See the License for the specific
+ * language governing permissions and limitations under the License.
+ *
+ ****************************************************************************/
+/* @file  : port_api.c
+ * @brief : GPIO port API source code
+ * @date  : June 2019
+ *
+ * @note  : Add chip dependent feature and control hardware GPIO port
+ *
+ */
+#include "port_api.h"
+#include "pinmap.h"
+#include "gpio_api.h"
+
+PinName port_pin(PortName port, int pin_n)
+{
+    return (PinName)((port << PORT_SHIFT) | pin_n);
+}
+
+void port_init(port_t *obj, PortName port, int mask, PinDirection dir)
+{
+
+}
+
+void port_mode(port_t *obj, PinMode mode)
+{
+
+}
+
+void port_dir(port_t *obj, PinDirection dir)
+{
+
+}
+
+void port_write(port_t *obj, int value)
+{
+    *obj->reg_in = value;
+}
+
+int port_read(port_t *obj)
+{
+    return (*obj->reg_in);
+}
+