random: don't forget compat_ioctl on urandom

Recently, there's been some compat ioctl cleanup, in which large
hardcoded lists were replaced with compat_ptr_ioctl. One of these
changes involved removing the random.c hardcoded list entries and adding
a compat ioctl function pointer to the random.c fops. In the process,
urandom was forgotten about, so this commit fixes that oversight.

Fixes: 507e4e2b43 ("compat_ioctl: remove /dev/random commands")
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Link: https://lore.kernel.org/r/20191217172455.186395-1-Jason@zx2c4.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/char/random.c

@@ -2175,6 +2175,7 @@ const struct file_operations urandom_fops = {
 	.read  = urandom_read,
 	.write = random_write,
 	.unlocked_ioctl = random_ioctl,
+	.compat_ioctl = compat_ptr_ioctl,
 	.fasync = random_fasync,
 	.llseek = noop_llseek,
 };