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/compute_ip_checksum.c

@@ -15,7 +15,7 @@ unsigned long compute_ip_checksum(const void *addr, unsigned long length)
 	 */
 	sum = 0;
 	ptr = addr;
-	for(i = 0; i < length; i++) {
+	for (i = 0; i < length; i++) {
 		unsigned long v;
 		v = ptr[i];
 		if (i & 1)