clk: samsung: Rework clkdev alias handling in Exynos5440 driver

Exynos5440 still uses old, non-dt CPUfreq driver, which requires clkdev
aliases to get access to proper clocks. Create those aliases using
samsung_clk_register_alias() function instead of using *_A clock macros,
which will be removed soon.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>