hwrng: Add no-clock-support in msm_rng

PRNG HW design requires clock to always be enabled.
Dynamically enabling/disabling the PRNG clock is not
safe. This change is needed to bypass the PRNG clock
handle request from the HLOS side by adding support for
no-clock-support in MSM RNG driver.

Change-Id: I7cedb43f7d07d062c1c5dad71ccae00f331315c5
Signed-off-by: Anmolpreet Kaur <anmolpre@codeaurora.org>