nv30: Fix creation of scanout buffers

nv30: Fix creation of scanout buffers

Scanout buffers on nv30 must always be non-swizzled and have special
width alignment constraints.

These constrains have been taken from the xf86-video-nouveau
src/nv_accel_common.c: nouveau_allocate_surface() function.

nouveau_allocate_surface() applies these width constraints only when a
tiled attribute is set, which it sets for all surfaces allocated via
dri, and this "tiling" is not the same as swizzling, scanout surfaces
must be linear / have a uniform_pitch or only complete garbage is shown.

This commit fixes dri3 on nv30 showing a garbled display, with dri3 the
scanout buffers are allocated by mesa, rather then by the ddx, and the
wrong stride of these buffers was causing the garbled display.

Cc: "10.6 11.0" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>