configs: sunxi: OrangePi Zero: enable Macronix flash support

The boards that come with a flash memory pre-soldered have a Macronix
flash chip.

Fixes: 280294c5 ("sunxi: boards: Enable SPI flash support in U-Boot proper")
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>