ASoC: cs42l56: fix DT probe

While looking through legacy platform data users, I noticed that
the DT probing never uses data from the DT properties, as the
platform_data structure gets overwritten directly after it
is initialized.

There have never been any boards defining the platform_data in
the mainline kernel either, so this driver so far only worked
with patched kernels or with the default values.

For the benefit of possible downstream users, fix the DT probe
by no longer overwriting the data.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20230126162203.2986339-1-arnd@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>