msm: Ensure droop detectors do not affect krait PLLs

The Droop detector mechanism present in Glitch-Free (GFMUX)
goes to nondeterministic state during frequent
standalone power collapse operation. It affects
Krait PLL output so that the PLL won't lock to
required frequency.

Since Droop detector isn't used, set sc_pdn (PLL_CLAMP)
permanently high to ensure droop detector is off and it
does not affect Krait PLL.

CRs-Fixed: 381144
Change-Id: I94ee03e0e9439c5195909a8646ff9e3c3f667893
Signed-off-by: Jay Chokshi <jchokshi@codeaurora.org>