Fix dt-binding-check issue

ti,gpi-config:0:0: 4 is greater than the maximum of 1
ti,gpi-config:0:1: 5 is greater than the maximum of 1
ti,gpi-config:0:2: 6 is greater than the maximum of 1
ti,gpi-config:0:3: 7 is greater than the maximum of 1
Reported-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dan Murphy <dmurphy@ti.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200528144711.18065-1-dmurphy@ti.comSigned-off-by: Mark Brown <broonie@kernel.org>