net: renesas: Enable TFTP_TSIZE on all Renesas hardware

TFTP transfer size can be used to re-size the TFTP progress bar on
single line based on the server reported file size. Enable it by
default for Renesas hardware to avoid long scrolling walls of '#'
character during long TFTP transfers.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>