drm/qxl: add support for > 1 output

This adds support for a default of 4 heads, with a command line
parameter to change the default number.

It also overhauls the modesetting code to handle this case properly,
and send the correct things to the hardware at the right time.

Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/qxl/qxl_drv.c b/drivers/gpu/drm/qxl/qxl_drv.c
index aa291d8a..00e57b76 100644
--- a/drivers/gpu/drm/qxl/qxl_drv.c
+++ b/drivers/gpu/drm/qxl/qxl_drv.c
@@ -47,10 +47,14 @@
 MODULE_DEVICE_TABLE(pci, pciidlist);
 
 static int qxl_modeset = -1;
+int qxl_num_crtc = 4;
 
 MODULE_PARM_DESC(modeset, "Disable/Enable modesetting");
 module_param_named(modeset, qxl_modeset, int, 0400);
 
+MODULE_PARM_DESC(num_heads, "Number of virtual crtcs to expose (default 4)");
+module_param_named(num_heads, qxl_num_crtc, int, 0400);
+
 static struct drm_driver qxl_driver;
 static struct pci_driver qxl_pci_driver;