ASoC: dt-bindings: cirrus,cs42l43: Fix 'gpio-ranges' schema

'gpio-ranges' is a phandle-array which is really a matrix. The schema in
cirrus,cs42l43 is incomplete as it doesn't define there's only a single
entry. Add the outer array constraints that there is a single entry.

Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://msgid.link/r/20240311222554.1940567-1-robh@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>