ASoC: samsung: Rename samsung i2s secondary device name

All Samsung SoCs has max 3 i2s controllers. So the i2s secondary fifo
interface device id was named as samsung-i2s.4. Renaming this to
"samsung-i2s-sec" to support device tree in i2s driver.

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