drm/i915: index gmbus tables using the pin pair number

Index the gmbus tables directly using the pin instead of having a
confusing "port = i + 1" mapping. This finishes off removing the "gmbus
port" as a notion, and leaves us with just the "gmbus pin".

As pin 0 is invalid by definition and the gmbus tables will have a gap
at that index, add pin validity check to all the loops. This will be
benefitial for supporting platforms that have different numbers of pins,
or gaps.

v2: s/GMBUS_PIN_MAX/GMBUS_NUM_PINS/ (Ville, Daniel)

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index b0390c8..0ad11d9 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1574,8 +1574,7 @@
 
 	struct i915_virtual_gpu vgpu;
 
-	struct intel_gmbus gmbus[GMBUS_NUM_PORTS];
-
+	struct intel_gmbus gmbus[GMBUS_NUM_PINS];
 
 	/** gmbus_mutex protects against concurrent usage of the single hw gmbus
 	 * controller on different i2c buses. */