clean-up trailing whitespace (#453)

These changes have been mostly auto-generated with:

	find . -type f -print0 | xargs -0 perl -pi -e 's/ +$//'

Signed-off-by: Radostin Stoyanov <rstoyanov@fedoraproject.org>

exercises/qos/qos.p4

@@ -159,8 +159,8 @@ control MyEgress(inout headers hdr,
 control MyComputeChecksum(inout headers hdr, inout metadata meta) {
     apply {
         /* TODO: replace tos with diffserv and ecn */
-	update_checksum(
-	    hdr.ipv4.isValid(),
+        update_checksum(
+            hdr.ipv4.isValid(),
             { hdr.ipv4.version,
               hdr.ipv4.ihl,
               hdr.ipv4.tos,