fs: Add a FSTAB_ENTRY_DT_*_MOUNT_POINT macros

These macros provide a way to get the `mount-point` value from
an fstab entry:
- FSTAB_ENTRY_DT_MOUNT_POINT
- FSTAB_ENTRY_DT_INST_MOUNT_POINT

Signed-off-by: James Roy <[email protected]>

Author: rruuaanng

include/zephyr/fs/fs.h

@@ -206,6 +206,24 @@ struct fs_statvfs {
 	 | (DT_PROP(node_id, no_format) ? FS_MOUNT_FLAG_NO_FORMAT : 0)  \
 	 | (DT_PROP(node_id, disk_access) ? FS_MOUNT_FLAG_USE_DISK_ACCESS : 0))
 
+/**
+ * @brief Get the mount-point from an fstab entry.
+ *
+ * @param node_id The node identifier for a child entry in a zephyr,fstab node.
+ * @return The mount-point path.
+ */
+#define FSTAB_ENTRY_DT_MOUNT_POINT(node_id) \
+	DT_PROP(node_id, mount_point)
+
+/**
+ * @brief Get the mount-point from an fstab entry.
+ *
+ * @param inst Instance number
+ * @return The mount-point path.
+ */
+#define FSTAB_ENTRY_DT_INST_MOUNT_POINT(inst) \
+	DT_INST_PROP(inst, mount_point)
+
 /**
  * @brief The name under which a zephyr,fstab entry mount structure is
  * defined.