firmware: qcom_scm: Add gpu_init_regs call

This will used by drm/msm to initialize GPU registers that Qualcomm's
firmware doesn't make writeable to the kernel.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Connor Abbott <cwabbott0@gmail.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Acked-by: Bjorn Andersson <andersson@kernel.org>
Patchwork: https://patchwork.freedesktop.org/patch/592039/


Signed-off-by: Rob Clark <robdclark@chromium.org>