hwrng: Add QRNG driver snapshot for sdm855.

This is a snapshot of the qrng driver as of the msm-4.9
commit <249f073d39e9d33> (Merge "diag: Prevent unnecessary
data ready counter update").

Change-Id: I4ac2e798415c7012ae260206136c2833fab4ea2c
Signed-off-by: Zhen Kong <zkong@codeaurora.org>