clk: msm: clock-gpu-8998: Program the Droop Detector gfx_pdn

In order to avoid leakage between the graphics and the CX
rails, set the GPU_DD_WRAP_CTRL__GFX_PDN bit.

Change-Id: I7b2e59606e73c467c2b862f0162a176611d7ae3d
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>