Collapse urandom_device into random_device

urandom_device and random_device have the exact same security
properties. Collapse them into one type.

Test: device boots and /dev/urandom is labeled correctly.
Change-Id: I12da30749291bc5e37d99bc9422bb86cb58cec41
diff --git a/private/file_contexts b/private/file_contexts
index f1d736d..e0e9d08 100644
--- a/private/file_contexts
+++ b/private/file_contexts
@@ -134,7 +134,7 @@
 /dev/uhid		u:object_r:uhid_device:s0
 /dev/uinput		u:object_r:uhid_device:s0
 /dev/uio[0-9]*		u:object_r:uio_device:s0
-/dev/urandom		u:object_r:urandom_device:s0
+/dev/urandom		u:object_r:random_device:s0
 /dev/usb_accessory	u:object_r:usbaccessory_device:s0
 /dev/vcs[0-9a-z]*	u:object_r:vcs_device:s0
 /dev/video[0-9]*	u:object_r:video_device:s0