ASoC: tlv320aic31xx: Fix GPIO1 register definition

GPIO1 control register is number 51, fix this here.

Fixes: bafcbfe4

 ("ASoC: tlv320aic31xx: Make the register values human readable")
Signed-off-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org