ASoC: qcom/lpass: Constify struct lpass_variant

'struct lpass_variant' is used for driver match data which is supposed to
be constant. It's not modified anywhere, so it's just a matter of adding
'const' everywhere.

Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20231006-dt-asoc-header-cleanups-v3-4-13a4f0f7fee6@kernel.org


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