hw/arm/iotkit: Rename IoTKit to ARMSSE

hw/arm/iotkit: Rename IoTKit to ARMSSE

The Arm IoTKit was effectively the forerunner of a series of
subsystems for embedded SoCs, named the SSE-050, SSE-100 and SSE-200:
https://developer.arm.com/products/system-design/subsystems
These are generally quite similar, though later iterations have
extra devices that earlier ones do not.

We want to add a model of the SSE-200, which means refactoring the
IoTKit code into an abstract base class and subclasses (using the
same design that the bcm283x SoC and Aspeed SoC family
implementations do). As a first step, rename the IoTKit struct and
QOM macros to ARMSSE, which is what we're going to name the base
class. We temporarily retain TYPE_IOTKIT to avoid changing the
code that instantiates a TYPE_IOTKIT device here and then changing
it back again when it is re-introduced as a subclass.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190121185118.18550-5-peter.maydell@linaro.org