kunit: string-stream-test: Include <linux/prandom.h>

Include <linux/random.h> header to allow the removal of legacy
inclusion of <linux/prandom.h> from <linux/random.h>.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: David Gow <davidgow@google.com>
Cc: Rae Moar <rmoar@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

lib/kunit/string-stream-test.c

@@ -9,6 +9,7 @@
 #include <kunit/static_stub.h>
 #include <kunit/test.h>
 #include <linux/ktime.h>
+#include <linux/prandom.h>
 #include <linux/slab.h>
 #include <linux/timekeeping.h>