Actually assign VSC_PIPE's properly, which will be needed for tiling.
And introduce fd_tile for per-tile state (including the assignment of
tile to VSC_PIPE).  This gives us the proper pipe setup that we'll
need for hw binning pass, and also cleans things up a bit by not having
to pass so many parameters around.  And will also make it easier to
introduce different tiling patterns (since we may no longer render
tiles in a simple left-to-right top-to-bottom pattern).

Signed-off-by: Rob Clark <robclark@freedesktop.org>