hw/arm/exynos4210: Put a9mpcore device into state struct

The exynos4210 SoC mostly creates its child devices as if it were
board code.  This includes the a9mpcore object.  Switch that to a
new-style "embedded in the state struct" creation, because in the
next commit we're going to want to refer to the object again further
down in the exynos4210_realize() function.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220404154658.565020-4-peter.maydell@linaro.org
2 files changed