Add /dev/frandom support

Change-Id: I0234433f5a397dc71b1d2ed4f7c4cba6df9f1ef7
Signed-off-by: flar2 <asegaert@gmail.com>
defconfig: enable frandom

Change-Id: I948e7a04621e4c8aea6a7aa846aabc9ee4f064b8