allwinner: power: add enable switches for DCDC1/5

The DCDC1 and DCDC5 power rails didn't specify the enable bits. This
isn't critical, since those rails are on by default (and are needed for
every board), but it is inconsistent.

Add the respective enable bits for those two rails.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>