i965/disasm: Stop using gen8_disassemble in favor of brw_disassemble.

i965/disasm: Stop using gen8_disassemble in favor of brw_disassemble.

At this point, brw_disassemble can do everything gen8_disassemble can
do - and, thanks to the new brw_inst API, it supports all generations.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>