ARM: versatile: merge mach code into a single file

With DT-only support now in place and most of the legacy code removed,
the separation of core.c and versatile_dt.c makes little sense. The
headers in mach include directory also have to move for multi-platform
support, but with a single .c file the remaining definitions needed can
also be moved into the versatile_dt.c.

In the move, the system registers and IB2 registers are converted to
run-time mappings and all register accesses converted to use
readl/writel.

Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>