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>
diff --git a/drivers/mtd/tests/stresstest.c b/drivers/mtd/tests/stresstest.c
index 75b6ddc..8062098 100644
--- a/drivers/mtd/tests/stresstest.c
+++ b/drivers/mtd/tests/stresstest.c
@@ -46,7 +46,7 @@ static int rand_eb(void)
 
 again:
 	/* Read or write up 2 eraseblocks at a time - hence 'ebcnt - 1' */
-	eb = prandom_u32_max(ebcnt - 1);
+	eb = get_random_u32_below(ebcnt - 1);
 	if (bbt[eb])
 		goto again;
 	return eb;
@@ -54,12 +54,12 @@ static int rand_eb(void)
 
 static int rand_offs(void)
 {
-	return prandom_u32_max(bufsize);
+	return get_random_u32_below(bufsize);
 }
 
 static int rand_len(int offs)
 {
-	return prandom_u32_max(bufsize - offs);
+	return get_random_u32_below(bufsize - offs);
 }
 
 static int do_read(void)
@@ -118,7 +118,7 @@ static int do_write(void)
 
 static int do_operation(void)
 {
-	if (prandom_u32_max(2))
+	if (get_random_u32_below(2))
 		return do_read();
 	else
 		return do_write();