cppcheck: (error) Uninitialized variable

As of cppcheck 1.82 warnings are issued when using the list_for_each_*
functions with an uninitialized variable.  Functionally, this is fine
but to resolve the warning initialize these variables.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #9732

module/os/linux/spl/spl-generic.c

@@ -697,7 +697,7 @@ static void __init
 spl_random_init(void)
 {
 	uint64_t s[2];
-	int i;
+	int i = 0;
 
 	get_random_bytes(s, sizeof (s));