OMAP3: igep00x0: add CONFIG_SYS_NS16550_BROKEN_TEMT

IGEP board PC16550D (ns16550) UART doesn't set the
Transmitter Empty (TEMT) Bit in SPL. This makes
U-Boot to hang while waiting for TEMT. Add the
CONFIG_SYS_NS16550_BROKEN_TEMT config option to
avoid this issue.

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>