i965/blorp: Thread level and layer through brw_blorp_blit_miptrees().

i965/blorp: Thread level and layer through brw_blorp_blit_miptrees().

Previously, when performing a blit using the blorp engine, we failed
to account for the level and layer of the source and destination.  As
a result, all blits would occur between miplevel 0 and layer 0 of the
corresponding textures, regardless of which level/layer was bound to
the framebuffer.

This patch passes the correct level and layer through
brw_blorp_miptrees() into the brw_blorp_blit_params data structure.

Further patches in the series will adapt
gen{6,7}_blorp_emit_surface_state to make use of these parameters.

NOTE: This is a candidate for stable release branches.

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