ASoC: Intel: sof_sdw: add missing sof_sdw_rt_amp_init for Realtek multi-function codecs

We do need "info->amp_num++;" for the speaker dai.

Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20240411220347.131267-2-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>