radeon_cs_setup_bo: Fix accounting if caller specified write and read domains.

Only account for the write domain in that case.

Fixes https://bugs.freedesktop.org/show_bug.cgi?id=43893

 .

Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>