clk: samsung: Add S5PV210 Audio Subsystem clock driver

This patch adds a driver for clock controller being a part of Audio
Subsystem present on S5PV210 and compatible SoCs. It is used to provide
clocks for other IP blocks of this subsystem.

Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>