drm/i915: Fix GPIO pin to register mapping

In i2c GPIO fallback, index 6 is reserved for nothing.
Signed-off-by: NZhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/intel_i2c.c

@@ -155,6 +155,7 @@ intel_gpio_create(struct drm_i915_private *dev_priv, u32 pin)
 		GPIOC,
 		GPIOD,
 		GPIOE,
+		0,
 		GPIOF,
 	};
 	struct intel_gpio *gpio;