configs: mvebu_espressobin_ultra-88f3720_defconfig: enable full bootflow functionality

This appliance has multiple devices from which it can boot. Enable full
bootflow functionality so users can choose a non-default boot device.

Signed-off-by: Ben Schneider <ben@bens.haus>
Reviewed-by: Stefan Roese <sr@denx.de>
1 file changed