sunxi: defconfig: Add Lctech Pi F1C200s board

The Lctech Pi F1C200s (also previously known under the Cherry Pi brand)
is a small development board with the Allwinner F1C200s SoC. This is the
same as the F1C100s, but with 64MB instead of 32MB co-packaged DRAM.

Add a defconfig for this board, enabling the most basic features. This
uses the new 64MB memory map, which avoids the very tight memory map we
use for the 32MB F1C100s board(s).
The devicetree file is already in the tree, courtesy of the previous
Linux repo sync.

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