sunxi: Add support for H616 SoC

H616 is very similar to H6 so most of the infrastructure can be reused.
However, two big differences are that it doesn't have functional SRAM A2
which is usually used for TF-A and it doesn't have ARISC co-processor.
It also needs bigger SPL size - 48 KiB.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>