clk: samsung: Remove clkdev alias support in Exynos5250 clk driver

All Exynos5250 boards have been fully converted to device-tree and use
generic dt-based CPUfreq driver, so there is no need to create any clkdev
aliases for the clocks. Drop all the code related to aliases handling.

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>