treewide: use get_random_u32_below() instead of deprecated function

This is a simple mechanical transformation done by:

@@
expression E;
@@
- prandom_u32_max
+ get_random_u32_below
  (E)

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs
Reviewed-by: SeongJae Park <sj@kernel.org> # for damon
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> # for infiniband
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> # for arm
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

kernel/locking/test-ww_mutex.c

@@ -399,7 +399,7 @@ static int *get_random_order(int count)
 		order[n] = n;
 
 	for (n = count - 1; n > 1; n--) {
-		r = prandom_u32_max(n + 1);
+		r = get_random_u32_below(n + 1);
 		if (r != n) {
 			tmp = order[n];
 			order[n] = order[r];
@@ -538,7 +538,7 @@ static void stress_one_work(struct work_struct *work)
 {
 	struct stress *stress = container_of(work, typeof(*stress), work);
 	const int nlocks = stress->nlocks;
-	struct ww_mutex *lock = stress->locks + prandom_u32_max(nlocks);
+	struct ww_mutex *lock = stress->locks + get_random_u32_below(nlocks);
 	int err;
 
 	do {