ARM: omap: Enable tiny printf on omap3_logic

Enable support for tiny printf on the omap3_logic board to trim down
the SPL size. This makes the SPL actually build again and fit into
the SRAM.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>
Cc: lesne@alse-fr.com
Reviewed-by: Tom Rini <trini@konsulko.com>