drm: qxl: Drop misleading comment

No longer true since commit 07f8d9bd ("drm/qxl: add support for > 1
output").  qxl_num_crtc defaults to 4 and is configurable as a module
parameter.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.co.uk>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170127010548.27970-1-krisman@collabora.co.uk


Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>