src/lib: Wrap lines at 80 columns

Fix the following warning detected by checkpatch.pl:

WARNING: line over 80 characters

TEST=Build and run on Galileo Gen2

Change-Id: I5fa3f8e950e2f0c60bd0e8f030342dc8c0469299
Signed-off-by: Lee Leahy <Leroy.P.Leahy@intel.com>
Reviewed-on: https://review.coreboot.org/18758
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

src/lib/compute_ip_checksum.c

@@ -31,7 +31,8 @@ unsigned long compute_ip_checksum(const void *addr, unsigned long length)
 	return (~value.word) & 0xFFFF;
 }
 
-unsigned long add_ip_checksums(unsigned long offset, unsigned long sum, unsigned long new)
+unsigned long add_ip_checksums(unsigned long offset, unsigned long sum,
+	unsigned long new)
 {
 	unsigned long checksum;
 	sum = ~sum & 0xFFFF;