hw/arm/exynos4210: Zero memory allocated for Exynos4210State

In exynos4210_init() we allocate memory for an Exynos4210State
struct. Generally devices can assume that the memory allocated
for their state struct is zero-initialized; we broke that
assumption here by using g_new(). Use g_new0() instead.
(In particular, some code assumes that the various irq arrays
in the Exynos4210Irq sub-struct are zero-initialized.)

In the longer term, this code should be QOMified, and then
the struct memory will be allocated elsewhere and by functions
which always zero-initalize it; but for 3.1 this is a
simple fix.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20181105151132.13884-1-peter.maydell@linaro.org