ARM: EXYNOS: Add Exynos3250 SoC ID

This patch add Exynos3250's SoC ID. Exynos 3250 is SoC that
is based on the 32-bit RISC processor for Smartphone.
Exynos3250 uses Cortex-A7 dual cores and has a target speed
of 1.0GHz.

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>