The checkboard() function showing hard-coded board model for which the
U-Boot was built is superseded on Gen3 by show_board_info() displaying
the Model from device tree. Add small ifdef to stop compiling the
function into U-Boot.
Signed-off-by: NMarek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>