src/lib: Add space before (

Fix the following error detected by checkpatch.pl:

ERROR: space required before the open parenthesis '('

TEST=Build and run on Galileo Gen2

Change-Id: I8953fecbe75136ff989c9e3cf6c5e155dcee3c3b
Signed-off-by: Lee Leahy <Leroy.P.Leahy@intel.com>
Reviewed-on: https://review.coreboot.org/18698
Reviewed-by: Philippe Mathieu-Daudé <philippe.mathieu.daude@gmail.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

src/lib/stack.c

@@ -41,7 +41,7 @@ int checkstack(void *top_of_stack, int core)
 		return -1;
 	}
 
-	for(i = 1; i < stack_size/sizeof(stack[0]); i++){
+	for (i = 1; i < stack_size/sizeof(stack[0]); i++){
 		if (stack[i] == 0xDEADBEEF)
 			continue;
 		printk(BIOS_SPEW, "CPU%d: stack: %p - %p, ",