ASoC: SDCA: Add generic regmap SDCA helpers

Add helper functions that SDCA drivers can use to calculate the
properties of SDCA Controls (registers) specified through DisCo.
Most of these are fairly obvious from the SDCA Access Modes.

DisCo Constants, values which are specified in the ACPI rather than on
the device, are handled as unreadable and unwritable registers. The
intention is these will be populated in the register defaults table
allowing drivers to read them normally. This means the drivers can be
agnostic as to which values are DisCo Constants.

Finally, support for SDCA Dual Ranked Controls is currently limited
here, at the moment the current value will be used directly. Writing
the current value directly is valid as per the specification
although the synchronicity of updates across multiple registers is
lost. Support for this will probably need to be added later. But its a
fairly hard problem and doesn't need to be solved immediately.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.dev>
Link: https://patch.msgid.link/20250217140159.2288784-3-ckeepax@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

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