ASoC: SDCA: Correct handling of selected mode DisCo property

ASoC: SDCA: Correct handling of selected mode DisCo property

mipi-sdca-ge-selectedmode-controls-affected is actually required by the
specification so the code should return an error if it is missing.

Reported-by: Maciej Strozek <mstrozek@opensource.cirrus.com>
Fixes: 13fe7497af19 ("ASoC: SDCA: Add support for GE Entity properties")
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://patch.msgid.link/20250321135324.380237-1-ckeepax@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>