drm: Don't pass the index to drm_property_add_enum()

drm_property_add_enum() can calculate the index itself just fine,
so no point in having the caller pass it in.

Cc: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: nouveau@lists.freedesktop.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180316190420.26734-1-ville.syrjala@linux.intel.com
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>

include/drm/drm_property.h

@@ -260,7 +260,7 @@ struct drm_property *drm_property_create_object(struct drm_device *dev,
 						uint32_t type);
 struct drm_property *drm_property_create_bool(struct drm_device *dev,
 					      u32 flags, const char *name);
-int drm_property_add_enum(struct drm_property *property, int index,
+int drm_property_add_enum(struct drm_property *property,
 			  uint64_t value, const char *name);
 void drm_property_destroy(struct drm_device *dev, struct drm_property *property);