drm/radeon: fix order of doing things in radeon_crtc_cursor_set
if object pin or object lookup in radeon_cursor_set fail, the function
could leave inconsistent mouse width and hight values in radeon_crtc
fixed by moving cursor width and height assignments after all
checks have passed
Signed-off-by: Ilija Hadzic <ihadzic@research.bell-labs.com> Reviewed-by: Alex Deucher <alexdeucher@gmail.com> Signed-off-by: Dave Airlie <airlied@redhat.com>