clk: exynos5433: Add CLK_SET_RATE_PARENT to support DVFS for big.LITTLE core

This patch adds CLK_SET_RATE_PARENT flag to support DVFS of Cortex-{A53|A57}
core (big.LITTLE core) because 'sclk_{apollo|atlas}' leaf clock is used to
change the CPU frequency of Cortex-{A53|A57} core in arm_big_little.c driver.
- 'apollo' word means the LITTLE core (Cortex-A53 core) in Exynos5433 TRM.
- 'atlas' word means the big core (Cortex-A57 core) in Exynos5433 TRM.

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>