ASoC: rockchip: add missing module.h include

Missing module.h in linux directory will cause compile error with randconfig,
like as:
sound/soc/rockchip/rockchip_i2s.c:526:20: error: expected declaration
specifiers or ‘...’ before string constant
MODULE_DESCRIPTION("ROCKCHIP IIS ASoC Interface");

Signed-off-by: xujianqun <xjq@rock-chips.com>
Signed-off-by: Mark Brown <broonie@linaro.org>