Cherry-pick from clear-linux patches:
https://github.com/clearlinux-pkgs/linux-kvm/0104-give-rdrand-some-credit.patch

try to credit rdrand/rdseed with some entropy

In VMs but even modern hardware, we're super starved for entropy, and while we can
and do wear a tin foil hat, it's very hard to argue that
rdrand and rdtsc add zero entropy.
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NJiufei Xue <jiufei.xue@linux.alibaba.com>