ASoC: samsung-idma: avoid 64-bit division

dma_addr_t may be 64 bit wide, which causes a build failure
when doing a division on it. Here it is safe to cast to an
u32 type, which avoids the problem.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Xia Kaixu <kaixu.xia@linaro.org>
Tested-by: Tushar Behera <tushar.behera@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>