Initial port of savage to FreeBSD for the AGP and !ShadowStatus case. Adds

    drm_mtrr_{add,del} for handling the MTRR setup. Still has a LOR issue
    with DRM_VERIFYAREA_READ/DRM_COPY_FROM_USER_UNCHECKED in savage_bci.c
    -- this won't work with the fine-grained locking in use, and just doing
    a single copyin to a temporary will probably work fine. Also note that
    the module leaks approximately 4 kb on unload.