spi: cs42l43: Don't support sidecar properties on device tree systems

spi: cs42l43: Don't support sidecar properties on device tree systems

On some systems the cs42l43 has amplifiers attached to its
SPI controller that are not properly defined in ACPI. However,
this exists to provide compatibility with existing Windows ACPI.

On device tree systems this functionality should never be used,
there is no reason not to specify the amplifiers properly through
device tree.  Make this more clear by only allowing the "sidecar"
functionality to be used on non-DT systems.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://patch.msgid.link/20260223100717.4011114-1-ckeepax@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>