ASoC: Fix wrong define for AD1836_ADC_WORD_OFFSET

According to the datasheet:
The BIT[5:4] of ADC Control Register 2 is to control the word width.
        00 = 25 Bits
        01 = 20 Bits
        10 = 16 Bits
        11 = Invalid

Thus, the AD1836_ADC_WORD_OFFSET should be defined as 4.
Signed-off-by: NAxel Lin <axel.lin@gmail.com>
Acked-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Cc: stable@vger.kernel.org

sound/soc/codecs/ad1836.h

@@ -34,7 +34,7 @@
 
 #define AD1836_ADC_CTRL2               13
 #define AD1836_ADC_WORD_LEN_MASK       0x30
-#define AD1836_ADC_WORD_OFFSET         5
+#define AD1836_ADC_WORD_OFFSET         4
 #define AD1836_ADC_SERFMT_MASK         (7 << 6)
 #define AD1836_ADC_SERFMT_PCK256       (0x4 << 6)
 #define AD1836_ADC_SERFMT_PCK128       (0x5 << 6)