ASoC: wm8962: Do not remove ADDITIONAL_CONTROL_4 from readable register list

Removing ADDITIONAL_CONTROL_4 from the list of readable registers cause
audio distortion.

This change was sent as a comment below the --- line when submitting
commit 658bb297 ("ASoC: wm8962: Do not access WM8962_GPIO_BASE"), so
it was not supposed to get merged.

Keep WM8962_ADDITIONAL_CONTROL_4 inside wm8962_readable_register() to
fix the regression.

Fixes: 658bb297 ("ASoC: wm8962: Do not access WM8962_GPIO_BASE")
Reported-by: Shengjiu Wang <shengjiu.wang@gmail.com>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Link: https://lore.kernel.org/r/20200803115233.19034-1-festevam@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/wm8962.c

@@ -151,7 +151,6 @@ static const struct reg_default wm8962_reg[] = {
 	{ 40, 0x0000 },   /* R40    - SPKOUTL volume */
 	{ 41, 0x0000 },   /* R41    - SPKOUTR volume */
 
-	{ 48, 0x0000 },   /* R48    - Additional control(4) */
 	{ 49, 0x0010 },   /* R49    - Class D Control 1 */
 	{ 51, 0x0003 },   /* R51    - Class D Control 2 */
 
@@ -842,6 +841,7 @@ static bool wm8962_readable_register(struct device *dev, unsigned int reg)
 	case WM8962_SPKOUTL_VOLUME:
 	case WM8962_SPKOUTR_VOLUME:
 	case WM8962_THERMAL_SHUTDOWN_STATUS:
+	case WM8962_ADDITIONAL_CONTROL_4:
 	case WM8962_CLASS_D_CONTROL_1:
 	case WM8962_CLASS_D_CONTROL_2:
 	case WM8962_CLOCKING_4: