clk: samsung: exynos4: Disable ARMCLK down feature on Exynos4210 SoC

Commit 42773b28 ("clk: samsung: exynos4: Enable ARMCLK
down feature") enabled ARMCLK down feature on all Exynos4
SoCs.  Unfortunately on Exynos4210 SoC ARMCLK down feature
causes a lockup when ondemand cpufreq governor is used.
Fix it by limiting ARMCLK down feature to Exynos4x12 SoCs.

This patch was tested on:
- Exynos4210 SoC based Trats board
- Exynos4210 SoC based Origen board
- Exynos4412 SoC based Trats2 board
- Exynos4412 SoC based Odroid-U3 board

Cc: Daniel Drake <drake@endlessm.com>
Cc: Tomasz Figa <t.figa@samsung.com>
Cc: Kukjin Kim <kgene@kernel.org>
Fixes: 42773b28

 ("clk: samsung: exynos4: Enable ARMCLK down feature")
Cc: <stable@vger.kernel.org> # v3.17+
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Michael Turquette <mturquette@linaro.org>