drm/msm/hdmi: Add missing check for alloc_ordered_workqueue

drm/msm/hdmi: Add missing check for alloc_ordered_workqueue

Add check for the return value of alloc_ordered_workqueue as it may return
NULL pointer and cause NULL pointer dereference in `hdmi_hdcp.c` and
`hdmi_hpd.c`.

Fixes: c6a57a50ad56 ("drm/msm/hdmi: add hdmi hdcp support (V3)")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/517211/
Link: https://lore.kernel.org/r/20230106023011.3985-1-jiasheng@iscas.ac.cn
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>