i965: Implement interface to edit binding table entries

i965: Implement interface to edit binding table entries

Unlike normal software binding tables where the driver has to manually
generate and fill a binding table array which are then uploaded to the
hardware, the resource streamer instead presents the driver with an option
to fill out slots for individual binding table indices. The hardware
accumulates the state for these combined edits which it then automatically
flushes to a binding table pool when the binding table pointer state
command is invoked.

v2: Clarify binding table edit bit aligment (Topi).
v3: Make comments and function names more clearer (Ken).

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>