ASoC: ops: Factor out common code from info callbacks

snd_soc_info_volsw() and snd_soc_info_volsw_sx() do very similar
things, and have a lot of code in common. Already this is causing
some issues as the detection of volume controls has been fixed
in the normal callback but not the sx callback. Factor out a new
helper containing the common code and leave the function specific
bits behind in each callback.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://patch.msgid.link/20250318171459.3203730-12-ckeepax@opensource.cirrus.com


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