drm/bochs: switch fb_ops over to use drm_fb_helper_cfb helpers

drm/bochs: switch fb_ops over to use drm_fb_helper_cfb helpers

The current drm_fb_helper_sys helpers referenced in fb_ops assume that the
video memory is in system RAM. This is not the case for sparc which uses direct
physical memory accesses for IO memory and causes the bochs_drm module to panic
immediately upon startup as it tries to initialise the framebuffer.

Switching fb_ops over to use the drm_fb_helper_cfb helpers ensures that the
correct accesses are used on sparc, fixing the panic and allowing the
bochs_drm module to function under qemu-system-sparc64.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1499032363-8290-1-git-send-email-mark.cave-ayland@ilande.co.uk
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>