Untangle directory traversal into a simple iterator, to replace the
existing multi-purpose do_fat_read_at() + get_dentfromdir().
Change-Id: Iacf404e2ac7796adfa489d6e098c4d310635975a
Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Łukasz Majewski <lukma@denx.de>
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
(cherry picked from commit c6e3baa565bc3b5828cf0d67ca6429dbe5f8687c)