ASoC: sdw_utils: generate combined spk components string

The suggestion from UCM for 2 speaker components is using 1 "spk" tag
with 2 component names. Like "spk:rt722+rt1320". The commit removes the
creation of the "spk" components in each rtd_init callback and creat the
string in asoc_sdw_rtd_init().

Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Shuming Fan <shumingf@realtek.com>
Link: https://patch.msgid.link/20250625140430.311865-3-yung-chuan.liao@linux.intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>