doc: do not show undocumented members

Avoid listing internal function in the public API documentation. After
enabling those doxygen configs, we go lots of errors and bad refs that
were fixed.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>

include/gpio.h

@@ -532,6 +532,9 @@ static inline int gpio_port_disable_callback(struct device *port)
  */
 __syscall int gpio_get_pending_int(struct device *dev);
 
+/**
+ * @internal
+ */
 static inline int _impl_gpio_get_pending_int(struct device *dev)
 {
 	struct gpio_driver_api *api;

include/i2s.h

@@ -176,6 +176,9 @@ typedef u8_t i2s_opt_t;
 #define I2S_OPT_LOOPBACK                    (1 << 7)
 
 
+/**
+ * @brief I2C Direction
+ */
 enum i2s_dir {
 	/** Receive data */
 	I2S_DIR_RX,

include/init.h

@@ -55,10 +55,16 @@ extern "C" {
  * @brief Run an initialization function at boot at specified priority,
  * and define device PM control function.
  *
- * @copydetails SYS_INIT
- * @param pm_control_fn Pointer to device_pm_control function.
- * Can be empty function (device_pm_control_nop) if not implemented.
+ * @details This macro lets you run a function at system boot.
+ *
  * @param drv_name Name of this system device
+ * @param init_fn Pointer to the boot function to run
+ * @param pm_control_fn Pointer to device_pm_control function.
+ *                      Can be empty function (device_pm_control_nop) if not
+ *                      implemented.
+ * @param level The initialization level, See DEVICE_INIT for details.
+ * @param prio Priority within the selected initialization level. See
+ * 	       DEVICE_INIT for details.
  */
 #define SYS_DEVICE_DEFINE(drv_name, init_fn, pm_control_fn, level, prio) \
 	DEVICE_DEFINE(_SYS_NAME(init_fn), drv_name, init_fn, pm_control_fn, \

include/misc/stack.h

@@ -79,7 +79,14 @@ static inline void stack_analyze(const char *name, const char *stack,
 {
 }
 #endif
-
+/**
+ * @brief Analyze stacks
+ *
+ * Use this macro to get information about stack usage
+ *
+ * @param name Name of the stack
+ * @param sym The symbol of the stack
+ */
 #define STACK_ANALYZE(name, sym) \
 	stack_analyze(name, K_THREAD_STACK_BUFFER(sym), \
 		      K_THREAD_STACK_SIZEOF(sym))

include/net/mqtt_types.h

@@ -74,6 +74,9 @@ struct mqtt_connect_msg {
 	u16_t password_len;
 };
 
+/**
+ * @brief MQTT Publish Message
+ */
 struct mqtt_publish_msg {
 	u8_t dup;
 	enum mqtt_qos qos;

include/net/net_core.h

@@ -78,6 +78,9 @@ struct net_if;
 #include <logging/sys_log.h>
 #include <string.h>
 
+/**
+ * @brief Net Verdict
+ */
 enum net_verdict {
 	NET_OK,		/** Packet has been taken care of */
 	NET_CONTINUE,	/** Packet has not been touched,