drm/msm/gpu: Fix crash on devices without devfreq support (v2)

Avoid going down devfreq paths on devices where devfreq is not
initialized.

v2: Change has_devfreq() logic [Dmitry]

Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Reported-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>
Fixes: 6aa89ae1

 ("drm/msm/gpu: Cancel idle/boost work on suspend")
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20220308184844.1121029-1-robdclark@gmail.com