ARM: mstar: Add machine for MStar/Sigmastar Armv7 SoCs

Initial support for the MStar/Sigmastar Armv7 based IP camera
and dashcam SoCs.

These chips are interesting in that they contain a Cortex-A7,
peripherals and system memory in a single tiny QFN package that
can be hand soldered allowing almost anyone to embed Linux
in their projects.

Signed-off-by: Daniel Palmer <daniel@0x0f.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>