drm/msm/dpu: move _dpu_plane_get_qos_lut to dpu_hw_util file

_dpu_plane_get_qos_lut() is not specific to just dpu_plane.
It can take any fill level and return the LUT matching it.
This can be used even for other modules like dpu_writeback.

Move _dpu_plane_get_qos_lut() to the common dpu_hw_util file
and rename it to _dpu_hw_get_qos_lut().

Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/483518/
Link: https://lore.kernel.org/r/1650984096-9964-13-git-send-email-quic_abhinavk@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>