i965: Enable hardware-generated binding tables on render path.

i965: Enable hardware-generated binding tables on render path.

This patch implements the binding table enable command which is also
used to allocate a binding table pool where where hardware-generated
binding table entries are flushed into. Each binding table offset in
the binding table pool is unique per each shader stage that are
enabled within a batch.

Also insert the required brw_tracked_state objects to enable
hw-generated binding tables in normal render path.

v2: - Use MOCS in binding table pool alloc for GEN8
    - Fix spurious offset when allocating binding table pool entry
      and start from zero instead.
v3: - Include GEN8 fix for spurious offset above.
v4: - Fixup wrong packet length in enable/disable hw-binding table
      for GEN8 (Ville).
    - Don't invoke HW-binding table disable command when we dont
      have resource streamer (Chris).
v5: - Reorder the state cache invalidate flush so it happens in-between
      enabling hw-generated binding tables and the previous sw-binding
      table GPU state (Chris).
v6: - Do the same fix in v5 for gen7_disable_hw_binding_tables().
    - Adhere to coding guidelines and make comments more informative.

Cc: kenneth@whitecape.org
Cc: syrjala@sci.fi
Cc: chris@chris-wilson.co.uk
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>