configs: omap3_logic: Enable CONFIG_SPL_ALLOC_BD

With bd_info dropped from the data section, the Logic PD OMAP3 boards
and AM3517 fail to boot. Enabling CONFIG_SPL_ALLOC_BD restores
them.

Fixes: 38d6b7eb ("spl: Drop bd_info in the data section")
Signed-off-by: Adam Ford <aford173@gmail.com>