ASoC: hdmi-codec: Report a change when the channel status moves

The put() callback of "IEC958 Playback Default" stores all 24 channel
status bytes and then returns 0. The core notifies userspace only on a
positive return, so a write that changes what the get() callback hands
back is never announced, and a mixer holding the control open keeps
showing the old value.

Compare the stored bytes and return 1 when they move, the way
snd_hda_spdif_default_put() does.

The same shape is in img-spdif-out and uniperif_player.

No board with this codec was to hand. The change is a comparison of
driver state with no hardware behaviour in it, and mixer-test counts the
missing notification as event_missing.

Fixes: 7a8e1d44211e ("ASoC: hdmi-codec: Add iec958 controls")
Signed-off-by: HyeongJun An <sammiee5311@gmail.com>
Assisted-by: Claude:claude-opus-5
Link: https://patch.msgid.link/20260915092515.2638542-1-sammiee5311@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>