dt-bindings: arm: mstar: Add compatible for Miyoo Mini

The Miyoo Mini is a SigmaStar SSD202D based retro emulation
device.

Add a compatible for it to the list of infinity2m devices.

Link: http://linux-chenxing.org/infinity2/miyoomini/


Signed-off-by: Daniel Palmer <daniel@0x0f.com>
Acked-by: Rob Herring <robh@kernel.org>