drm/nouveau: Make the MM aware of pre-G80 tiling.

This commit has also the following 3 bugfix commits squashed into it from
the nouveau git tree:

drm/nouveau: Fix up the tiling alignment restrictions for nv1x.
drm/nouveau: Fix up the nv2x tiling alignment restrictions.
drm/nv50: fix align typo for g9x

Signed-off-by: Francisco Jerez <currojerez@riseup.net>