freedreno/a6xx: Emit blitter dst with OUT_RELOCW

We're writing to the bo and the kernel needs to know for
fd_bo_cpu_prep() to work.

Fixes: f93e4312 ("freedreno/a6xx: Enable blitter")
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Kristian H. Kristensen <hoegsberg@chromium.org>
(cherry picked from commit 357ea7da)