kcsan: Use min() to fix Coccinelle warning

Fixes the following Coccinelle/coccicheck warning reported by
minmax.cocci:

	WARNING opportunity for min()

Use const size_t instead of int for the result of min().

Compile-tested with CONFIG_KCSAN=y.
Reviewed-by: Marco Elver <elver@google.com>
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

kernel/kcsan/debugfs.c

@@ -225,7 +225,7 @@ debugfs_write(struct file *file, const char __user *buf, size_t count, loff_t *o
 {
 	char kbuf[KSYM_NAME_LEN];
 	char *arg;
-	int read_len = count < (sizeof(kbuf) - 1) ? count : (sizeof(kbuf) - 1);
+	const size_t read_len = min(count, sizeof(kbuf) - 1);
 
 	if (copy_from_user(kbuf, buf, read_len))
 		return -EFAULT;