drirc/i965: add option to disable 565 configs and visuals

We have cases where we would not like to expose these.

v2: call the option allow_rgb565_configs for consistency
    with existing allow_rgb10_configs (Eric, Jason)

Signed-off-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

src/util/xmlpool/t_options.h

@@ -264,6 +264,11 @@ DRI_CONF_OPT_BEGIN_B(allow_rgb10_configs, def) \
 DRI_CONF_DESC(en,gettext("Allow exposure of visuals and fbconfigs with rgb10a2 formats")) \
 DRI_CONF_OPT_END
 
+#define DRI_CONF_ALLOW_RGB565_CONFIGS(def) \
+DRI_CONF_OPT_BEGIN_B(allow_rgb565_configs, def) \
+DRI_CONF_DESC(en,gettext("Allow exposure of visuals and fbconfigs with rgb565 formats")) \
+DRI_CONF_OPT_END
+
 /**
  * \brief Initialization configuration options
  */