sunxi: Fix H616 DRAM read calibration for dual rank

Although it isn't known what bit 0 in PHY reg 8 does, it's obvious that
it has to be set before read calibration and cleared afterwards. This is
already done for first rank, but not for second (copy & paste error.)

Fix it.

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>