ASoC: samsung: Remove unused "samsung-i2sv4" platform_device_id entry

"samsung-i2sv4" identifier was previously used for the I2S device
of the S5PV210 SoCs, it can be removed now when s5pv210 is a dt-only
platform.

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