Revert "fdt_support: Add multi-serial support for stdout fixup"

This reverts commit 3e303f74.

The fix up in the /aliases node does not work under the following
scenarios:
- Not every non-DM serial driver was written to have a driver name
  that conforms the format of "serial%d" or "eserial%d".
- With driver model serial, the stdio_devices[] stores the serial
  device node name in the device tree.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>