sunxi: fix H616 DRAM ODT support

Kconfig symbol is missing CONFIG_ prefix, so compiler will always
skip ODT configuration.

Fix symbol name.

Fixes: f4317dbd ("sunxi: Add H616 DRAM support")
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>