allocate framebuffer memory without sisfb, and a new ioctl to be used
by the X Server which tells the DRM what region of framebuffer memory
to allocate from. Also fixes a possibility to panic the kernel I
believe. Tested on linux with sisfb and FreeBSD (without sisfb) with
new DRI only.
pageflipping after a mode switch
take current page into account in AdjustFrame(); writing the CRTC offset
via the CP was probably a bad idea as this can happen asynchronously,
reverted
take frame offset into account when flipping pages
handle CRTC2 as well for pageflipping (untested)
preserve GEN_INT_CNTL on mode switches to prevent interrupts from getting
disabled