Let init restorecon /dev/random and /dev/urandom.

Bug: http://b/29622562
Change-Id: I21bc79f31ffd0b002b4a25d3ceefaf12f42f05c4

init.te

@@ -20,6 +20,9 @@ allow init properties_serial:file { write relabelto };
 allow init property_type:file { create_file_perms relabelto };
 # /dev/socket
 allow init { device socket_device }:dir relabelto;
+# /dev/random, /dev/urandom
+allow init random_device:chr_file relabelto;
+allow init urandom_device:chr_file relabelto;
 # /dev/device-mapper, /dev/block(/.*)?
 allow init tmpfs:{ chr_file blk_file } relabelfrom;
 allow init tmpfs:blk_file getattr;