Split out DaVinci DM6446-specific bits from more generic bits:
- Add a CONFIG_SOC_DM644X. All current boards use DM6446 chips;
DM6443 and DM6441 chips differ in available peripherals.
- Move most DM644X-specific bits from psc.c to a new dm644x.c file,
which is conditionally built. It provides device-specific setup.
Plus minor coding style and comment updates with respect to the PSC.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
f79043681f