ASoC: wm8904: Correct number of EQ registers

There are 24 EQ registers not 25, I suspect this bug came about because
the registers start at EQ1 not zero. The bug is relatively harmless as
the extra register written is an unused one.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org