synquacer: Add platform makefile and documentation

Add Makefile and plaform definations file.
My thanks to Daniel Thompson and Ard Biesheuvel for the bits and pieces
I've taken from their earlier work regarding build and deploy steps for
Developerbox based on Synquacer SoCs. They deserve much of the credit
for this work although, since I assembled and tested things, any blame
is probably mine.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
diff --git a/readme.rst b/readme.rst
index 3738c97..c87936c 100644
--- a/readme.rst
+++ b/readme.rst
@@ -182,7 +182,7 @@
 -  QEMU emulator
 -  Raspberry Pi 3 board
 -  RockChip RK3328, RK3368 and RK3399 SoCs
--  Socionext UniPhier SoC family
+-  Socionext UniPhier SoC family and SynQuacer SC2A11 SoCs
 -  Texas Instruments K3 SoCs
 -  Xilinx Zynq UltraScale + MPSoC