ASoC: samsung: Fix non-DT use of I2S controller

The changes in commit a5a56871

 (ASoC: samsung: add support for exynos7
I2S controller) introduce a new variant_regs structure in the driver data
which is now mandatory for accessing registers. Unfortunately this is only
hooked up for DT platforms so non-DT platforms like my primary development
platform for audio are broken by this change and crash on boot.

Since the only non-DT user of these device is s3c64xx fix this by making
the standard samsung-i2s device be of type I2Sv3 and add a new I2Sv4 name
to the platform data section, currently using the I2Sv5 information which
should be about right.

Signed-off-by: Mark Brown <broonie@kernel.org>