drm/i915: kick firmware fbs even when i915 fbdev is disabled

Otherwise we don't kick out firmware framebuffers like vesafb and
efifb when CONFIG_DRM_I915_FBDEV=n but CONFIG_FB=y.

There's still the pesky issue with vgacon which we should somehow
replace with the dummy console at least. We have a similar issue at
module un/reload, since vgacon state is terminally botched after
i915.ko has loaded in modeset mode. But this gets us a step further at
least.

v2: Use IS_ENABLED - I always get this wrong for tristates. Spotted by
Jani.
Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_dma.c

@@ -1405,7 +1405,7 @@ void i915_master_destroy(struct drm_device *dev, struct drm_master *master)
 	master->driver_priv = NULL;
 }
 
-#ifdef CONFIG_DRM_I915_FBDEV
+#if IS_ENABLED(CONFIG_FB)
 static void i915_kick_out_firmware_fb(struct drm_i915_private *dev_priv)
 {
 	struct apertures_struct *ap;