ARM: mstar: Add infinity2m support

ARM: mstar: Add infinity2m support

The infinity2m series of chips are like the other Mstar/Sigmastar
chips in that they have a Cortex A7 system with DDR memory integrated
in a single package.

The infinity2m chips are intended for recording the incoming streams
from IP cameras. So instead of video encoders they have video decoders,
instead of a camera interface they have display hardware and so on.

Aside from the above points the big difference about these chips is that
they include a second Cortex A7 core.

Signed-off-by: Daniel Palmer <daniel@0x0f.com>
Link: https://lore.kernel.org/r/20201201134330.3037007-5-daniel@0x0f.com'
Signed-off-by: Arnd Bergmann <arnd@arndb.de>