drm/msm: fix missing wq allocation error handling

drm/msm: fix missing wq allocation error handling

commit ca090c837b430752038b24e56dd182010d77f6f6 upstream.

Add the missing sanity check to handle workqueue allocation failures.

Fixes: c8afe684c95c ("drm/msm: basic KMS driver for snapdragon")
Cc: stable@vger.kernel.org      # 3.12
Cc: Rob Clark <robdclark@gmail.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/525102/
Link: https://lore.kernel.org/r/20230306100722.28485-8-johan+linaro@kernel.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>