ASoC: rk312x: fix duplicate const

SOC_ENUM_SINGLE_DECL already defined with const, removing
the duplicate const in rk312x_codec.c

Change-Id: I085b1faf99a9ccd3b06e4e642abc1bc43cc8bac7
Signed-off-by: Shunqian Zheng <zhengsq@rock-chips.com>

Author: ZhengShunQian

sound/soc/codecs/rk312x_codec.c

@@ -616,12 +616,12 @@ static const char *const rk312x_voice_call_path_mode[] = {
 		"OFF", "RCV", "SPK", "HP", "HP_NO_MIC", "BT"};
 
 
-static const SOC_ENUM_SINGLE_DECL(rk312x_playback_path_type, 0, 0,
-				  rk312x_playback_path_mode);
-static const SOC_ENUM_SINGLE_DECL(rk312x_capture_path_type, 0, 0,
-				  rk312x_capture_path_mode);
-static const SOC_ENUM_SINGLE_DECL(rk312x_voice_call_path_type, 0, 0,
-				  rk312x_voice_call_path_mode);
+static SOC_ENUM_SINGLE_DECL(rk312x_playback_path_type, 0, 0,
+			    rk312x_playback_path_mode);
+static SOC_ENUM_SINGLE_DECL(rk312x_capture_path_type, 0, 0,
+			    rk312x_capture_path_mode);
+static SOC_ENUM_SINGLE_DECL(rk312x_voice_call_path_type, 0, 0,
+			    rk312x_voice_call_path_mode);
 
 
 /* static int rk312x_codec_power_up(int type); */