fs: Add fs_get_type_name to return current filesystem name

Add fs_get_type_name so we can get the current filesystem type.

Signed-off-by: Alex Kiernan <alex.kiernan@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Joe Hershberger <joe.hershberger@ni.com>

include/fs.h

@@ -37,6 +37,16 @@ int fs_set_blk_dev(const char *ifname, const char *dev_part_str, int fstype);
  */
 int fs_set_blk_dev_with_part(struct blk_desc *desc, int part);
 
+/**
+ * fs_get_type_name() - Get type of current filesystem
+ *
+ * Return: Pointer to filesystem name
+ *
+ * Returns a string describing the current filesystem, or the sentinel
+ * "unsupported" for any unrecognised filesystem.
+ */
+const char *fs_get_type_name(void);
+
 /*
  * Print the list of files on the partition previously set by fs_set_blk_dev(),
  * in directory "dirname".