Input - arizona-haptics: Fix double lock of dapm_mutex

snd_soc_dapm_sync takes the dapm_mutex internally, but we currently take
it externally as well. This patch fixes this.

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