ASoC: rk3308_codec: add suppot 4ch/6ch recording for codec

Change-Id: I4d5dd2c7d0f81966db0faf226b130601dcfcd0cf
Signed-off-by: Xing Zheng <zhengxing@rock-chips.com>

Author: acgzx

sound/soc/codecs/rk3308_codec.c

@@ -617,6 +617,8 @@ static int rk3308_hw_params(struct snd_pcm_substream *substream,
 		cur_grp_max = 0;
 		break;
 	case 2:
+	case 4:
+	case 6:
 	case 8:
 		adc_aif1 |= RK3308_ADC_I2S_STEREO;
 		cur_grp_max = (params_channels(params) - 1) / 2;