drm/bochs: Store correct CRTC index in events

drm/bochs: Store correct CRTC index in events

Previously a negative pipe caused a special case to be triggered for
drivers that didn't have proper VBLANK support. The trigger for this
special case is now independent of the pipe, so the correct CRTC index
can now be stored in events.

v2: convert to use drm_crtc_send_vblank_event()

Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1450178476-26284-3-git-send-email-boris.brezillon@free-electrons.com
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>