exynos: fix compiler warnings on possibly uninitialized variables

This shouldn't really happen, but GCC doesn't seem to be capable of decuding these aren't practically used when not initialized. This isn't a place of manually tuned machine code where every clock cycle matters, so it's better to just initialize them to keep the compiler quiet.

Signed-off-by: Enrico Weigelt, metux IT consult info@metux.net