ASoC: Samsung: Get I2S src_clk from clock alias id.

As the I2S src clks are registered with clkdev using generic
connection id, driver can get the clk name using generic id.
So the variable representing the array of rclk src clks is
deleted.

Signed-off-by: Padmavathi Venna <padma.v@samsung.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>