cpufreq: dt: Add exynos5433 compatible to use generic cpufreq driver

This patch adds the exynos5433 compatible string for supporting
the generic cpufreq driver on Exynos5433.

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>