ARM: EXYNOS: Avoid passing the clks through platform data

I2S controller has an internal mux for RCLK source clks. The list
of source clk names were passed through platform data in non-dt case.
The variable holding the list of RCLK source clk names is not
required, as the list of clks need to be registered with clkdev
using generic connection id. This is required as part of adding DT
support for I2S controller driver.

Signed-off-by: Padmavathi Venna <padma.v@samsung.com>
Acked-by: Sangbeom Kim <sbkim73@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>