ASoC: SDCA: Fix some holes in the regmap readable/writeable helpers

ASoC: SDCA: Fix some holes in the regmap readable/writeable helpers

The current regmap readable/writeable helper functions always
allow the Next flag and allows any Control Number. Mask the Next
flag based on SDCA_ACCESS_MODE_DUAL which is the only Mode that
supports it. Also check that the Control Number is valid for
the given control.

Fixes: e3f7caf74b79 ("ASoC: SDCA: Add generic regmap SDCA helpers")
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://patch.msgid.link/20250718135432.1048566-2-ckeepax@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>