ASoC: wm8960: correct the max register value of mic boost pga

the max register value of mic boost pga should be 3.
Signed-off-by: Zidan Wang <zidan.wang@freescale.com>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/wm8960.c

@@ -234,9 +234,9 @@ SOC_SINGLE_TLV("Left Input Boost Mixer LINPUT3 Volume",
 SOC_SINGLE_TLV("Left Input Boost Mixer LINPUT2 Volume",
 	       WM8960_INBMIX2, 1, 7, 0, lineinboost_tlv),
 SOC_SINGLE_TLV("Right Input Boost Mixer RINPUT1 Volume",
-		WM8960_RINPATH, 4, 4, 0, micboost_tlv),
+		WM8960_RINPATH, 4, 3, 0, micboost_tlv),
 SOC_SINGLE_TLV("Left Input Boost Mixer LINPUT1 Volume",
-		WM8960_LINPATH, 4, 4, 0, micboost_tlv),
+		WM8960_LINPATH, 4, 3, 0, micboost_tlv),
 
 SOC_DOUBLE_R_TLV("Playback Volume", WM8960_LDAC, WM8960_RDAC,
 		 0, 255, 0, dac_tlv),