The driver doesn't support scaling, but when an atomic test is done
it repeatedly spits out this warning which isn't particularly useful.

So just remove the error message.

Cc: Xinliang Liu <z.liuxinliang@hisilicon.com>
Cc: Rongrong Zou <zourongrong@gmail.com>
Cc: Xinwei Kong <kong.kongxinwei@hisilicon.com>
Cc: Chen Feng <puck.chen@hisilicon.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Peter Griffin <peter.griffin@linaro.org>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1529622076-20386-1-git-send-email-john.stultz@linaro.org