ASoC: samsung: i2s: Ensure names of supplied clocks are unique

In order to support multiple instances of the I2S IP block the platform
device name is prepended to each clock registered by the driver.
The clock-output-names property is now not used, this should not cause
any issues as, for example, CDCLK clock is referenced through DT 'clocks'
property, not by name.

This change allows to have both I2S0 and I2S1 enabled simultaneously
on exynos5433 and working properly when #clock-cells property is specified
in respective DT nodes.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>