nv_crtc_set_display_start
head2_set_display_start = (crtc_set_display_start) nv_crtc_set_display_start;
head1_set_display_start = (crtc_set_display_start) nv_crtc_set_display_start;
status_t nv_crtc_set_display_start(uint32 startadd,uint8 bpp);