i965: Print access flags in INTEL_DEBUG=buf output.

i965: Print access flags in INTEL_DEBUG=buf output.

Being able to see the access mode of various mappings is incredibly
useful for debugging.  With this patch, INTEL_DEBUG=buf now shows
data such as:

   bo_create: buf 7 (bufferobj) 640b
   bo_map_gtt: 7 (bufferobj) -> 0x7fca1fae5000, WRITE ASYNC
   brw_bo_map_cpu: 7 (bufferobj) -> 0x7fca1fae4000, READ
   bo_map_gtt: 5 (bufferobj) -> 0x7fca1fad4000, WRITE ASYNC
   brw_bo_map_cpu: 7 (bufferobj) -> 0x7fca1fae4000, READ

which makes it easy to see that there are async GTT writes with
intervening CPU reads.

Reviewed-by: Matt Turner <mattst88@gmail.com>