fs: Add fs_dir_t_init() function

The fs_dir_t_init() function has been added that should be used
for initialization of fs_dir_t structures before passing them
to fs_open and other functions.

Signed-off-by: Andrzej Puzdrowski <andrzej.puzdrowski@nordicsemi.no>

include/fs/fs.h

@@ -234,6 +234,20 @@ static inline void fs_file_t_init(struct fs_file_t *zfp)
 	*zfp = (struct fs_file_t){ 0 };
 }
 
+/**
+ * @brief Initialize fs_dir_t object
+ *
+ * Initializes the fs_dir_t object; the function needs to be invoked
+ * on object before first use with fs_opendir.
+ *
+ * @param zdp Pointer to file object
+ *
+ */
+static inline void fs_dir_t_init(struct fs_dir_t *zdp)
+{
+	*zdp = (struct fs_dir_t){ 0 };
+}
+
 /**
  * @brief Open or create file
  *

include/fs/fs_interface.h

@@ -59,6 +59,8 @@ struct fs_file_t {
 /**
  * @brief Directory object representing an open directory
  *
+ * The object needs to be initialized with function fs_dir_t_init().
+ *
  * @param dirp Pointer to directory object structure
  * @param mp Pointer to mount point structure
  */