fs: nffs: Add NFFS filesystem support

This patch adds filesystem interface implementation for NFFS.
Default configuration for mem slabs sizes are the same as in Mynewt.

Origin: Original
Signed-off-by: Andrzej Kaczmarek <andrzej.kaczmarek@codecoup.pl>

include/fs/fs_interface.h

@@ -43,6 +43,8 @@ extern "C" {
 
 #ifdef CONFIG_FILE_SYSTEM_FAT
 #include <fs/fat_fs.h>
+#elif CONFIG_FILE_SYSTEM_NFFS
+#include <fs/nffs_fs.h>
 #endif
 
 #ifdef __cplusplus

include/fs/nffs_fs.h

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2017 Codecoup
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef _NFFS_FS_H_
+#define _NFFS_FS_H_
+
+#include <sys/types.h>
+#include <nffs/nffs.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+FS_FILE_DEFINE(struct nffs_file *fp);
+FS_DIR_DEFINE(struct nffs_dir *dp);
+
+#define MAX_FILE_NAME 256
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _NFFS_FS_H_ */