ASoC: nau8822: Disable internal PLL if freq_out is zero

After finishing the playback or recording, the machine driver might
call snd_soc_dai_set_pll(codec, pll_id, 0, 0, 0) to stop the internal
PLL, but with the codec driver nau8822, it will print error as below:
 nau8822 0-001a: Unsupported input clock 0
 fsl-asoc-card sound-nau8822: failed to stop FLL: -22

Refer to the function wm8962_set_fll() in the codec driver wm8962, if
the freq_out is zero, turn off the internal PLL and return 0.

Cc: David Lin <ctlin0@nuvoton.com>
Cc: John Hsu <kchsu0@nuvoton.com>
Cc: Seven Li <wtli@nuvoton.com>
Signed-off-by: Hui Wang <hui.wang@canonical.com>
Link: https://lore.kernel.org/r/20220530040151.95221-3-hui.wang@canonical.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/nau8822.c

@@ -726,6 +726,13 @@ static int nau8822_set_pll(struct snd_soc_dai *dai, int pll_id, int source,
 	struct nau8822_pll *pll_param = &nau8822->pll;
 	int ret, fs;
 
+	if (freq_out == 0) {
+		dev_dbg(component->dev, "PLL disabled\n");
+		snd_soc_component_update_bits(component,
+			NAU8822_REG_POWER_MANAGEMENT_1, NAU8822_PLL_EN_MASK, NAU8822_PLL_OFF);
+		return 0;
+	}
+
 	fs = freq_out / 256;
 
 	ret = nau8822_calc_pll(freq_in, fs, pll_param);