clk: samsung: exynos5420: Move sleep init function and PLL data to init section

The exynos5420_clk_sleep_init() function and arrays with initialization
data of PLLs can be moved to init section because they are referenced
only from other init-level symbols.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>