ARM: EXYNOS: Remove smp_init_cpus hook from platsmp.c

We can safely remove exynos_smp_init_cpus() hook from mach-exynos/platsmp.c,
as all SMP platforms in mach-exynos can rely on DT for CPU core description
instead of determining number of cores from the SCU.

Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>