ARM: clock: msm8916: Add dummy clock node for prng

Add dummy clock node for QUALCOMM random number generator in the clock
tree, which is required by the driver during initialization.

Change-Id: Ib84224983527b599276003a8bbe2896d525149a1
Signed-off-by: AnilKumar Chimata <anilc@codeaurora.org>