i965/bufmgr: Delete set_tiling

i965/bufmgr: Delete set_tiling

Entirely unused, and really shouldn't be used. The alloc functions already
take care of this. And even in a future where we're not going to
h/v-align tiled buffers in the bufmgr, but only in isl, I think we
still want to adjust the tiling mode in the bufmgr, since that ties in
closely to mmaps and stuff like that.

get_tiling is still needed for the import paths (until we have modifiers
everywhere).

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>