ASoC: samsung: export idma_reg_addr_init

The idma_reg_addr_init function is used by the samsung i2s driver,
which can be a loadable module, so we have to export this function.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>