ARM: mstar: SMP support

ARM: mstar: SMP support

This patch adds SMP support for MStar/Sigmastar chips that have a second core
like those in the infinity2m family.

So far only single and dual core chips have been found so this does
the bare minimum to boot the second core. From what I can tell not having
the "holding pen" code to handle multiple cores is fine if there is only
one core the will get booted. This might need to be reconsidered if chips
with more cores turn up.

Signed-off-by: Daniel Palmer <daniel@0x0f.com>
Link: https://lore.kernel.org/r/20201201134330.3037007-11-daniel@0x0f.com'
Signed-off-by: Arnd Bergmann <arnd@arndb.de>