i965/blorp: store surface width/height in brw_blorp_mip_info.

i965/blorp: store surface width/height in brw_blorp_mip_info.

Previously, gen{6,7}_blorp_emit_surface_state would look up the width
and height of the surface at the time they set up the surface state,
and then tweak it if necessary (it's necessary when a W-tiled surface
is being mapped as Y-tiled).  With this patch, we look up the width
and height when setting up the blit, and store them in
brw_blorp_mip_info.  This allows us to do the necessary tweak in the
brw_blorp_blit_params constructor (where it makes more sense).  It
also reduces the need to keep track of level and layer in
brw_blorp_mip_info, so that a future patch can eliminate them
entirely.

For consistency, this patch makes a similar change to the handling of
depth buffers when doing HiZ operations.

NOTE: This is a candidate for stable release branches.

Reviewed-by: Eric Anholt <eric@anholt.net>