i965/drm: Fold drm_bacon_gem_reset_stats into the callers.

i965/drm: Fold drm_bacon_gem_reset_stats into the callers.

We're going to get rid of drm_bacon_context shortly, so we'd have to
change the interface slightly.  It's basically just an ioctl wrapper
that isn't terribly bufmgr-related, so We may as well just combine it
with the code in brw_reset.c that actually uses it.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Jason Ekstrand <jason@jlekstrand.net>