Revert "drm/i915: Allow LVDS on pipe A on gen4+"

This reverts commit 0f3ee801.

Enabling LVDS on pipe A was causing excessive wakeups on otherwise idle
systems due to i915 interrupts. So restrict the LVDS to pipe B once more,
whilst the issue is properly diagnosed.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=16307Reported-and-tested-by: Enrico Bandiello <enban@postal.uv.es>
Poked-by: Florian Mickler <florian@mickler.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Adam Jackson <ajax@redhat.com>
Cc: stable@kernel.org

drivers/gpu/drm/i915/intel_lvds.c

@@ -875,8 +875,6 @@ void intel_lvds_init(struct drm_device *dev)
 
 	intel_encoder->clone_mask = (1 << INTEL_LVDS_CLONE_BIT);
 	intel_encoder->crtc_mask = (1 << 1);
-	if (IS_I965G(dev))
-		intel_encoder->crtc_mask |= (1 << 0);
 	drm_encoder_helper_add(encoder, &intel_lvds_helper_funcs);
 	drm_connector_helper_add(connector, &intel_lvds_connector_helper_funcs);
 	connector->display_info.subpixel_order = SubPixelHorizontalRGB;