drm/msm/hdmi: silence -EPROBE_DEFER warning

Silence a warning message due to an -EPROBE_DEFER error to help cleanup
the system boot log.

Signed-off-by: Brian Masney <masneyb@onstation.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>