arm64: dts: meson: g12: name spdifout consistently

arm64: dts: meson: g12: name spdifout consistently

g12 and sm1 are fairly similar when it comes to audio.
Both have 2 spdif outputs. While the 2nd output is named "spdifout_b" for
both, the 1st one is named 'spdifout' for g12 and 'spdifout_a' for sm1.

Use 'spdifout_a' for both instead.

This change does not fix any particular problem. The intent is just to make
it easier to have a common card definitions for platform designs using both
SoC families, when spdifout is used.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20230925135326.1689396-1-jbrunet@baylibre.com
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>