drm/i915: Make AGP=n work even on gen3

Most platforms din't hit this condition, but if we want to allow
building without agp we should also make this allowed on gen3.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index c3e9485..a19940f 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -158,7 +158,7 @@
 #if IS_ENABLED(CONFIG_AGP_INTEL)
 extern int intel_agp_enabled;
 #else
-static int intel_agp_enabled;
+static int intel_agp_enabled = 1;
 #endif
 
 static const struct intel_device_info intel_i830_info = {