ASoC: Make S3C64xx clock export function to return struct clk

This makes the interface usable with the s3c-iis-v2 rate calculator
and consistent with S3C2412.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

diff --cc sound/soc/s3c24xx/s3c64xx-i2s.c
Simple merge

diff --cc sound/soc/s3c24xx/s3c64xx-i2s.h
Simple merge