ARM: renesas: Drop unnecessary function ft_board_setup()

Marek explained on IRC, that ft_board_setup() is not used / necessary
at all. So its best to just drop it completely, as it interferes with
the cleanup of CONFIG_MAX_PCI_REGIONS (completely removed).

Signed-off-by: Stefan Roese <sr@denx.de>
Suggested-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>