samples/pktgen: Correct comments about the thread config

They all claimed to be two CPU examples using eth1, eth2 but
that is only true in one case!

Rob Jones pointed out spelling and grammar errors here, which I've
also corrected.

Cc: Rob Jones <rob.jones@codethink.co.uk>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/samples/pktgen/pktgen.conf-1-1-rdos b/samples/pktgen/pktgen.conf-1-1-rdos
index e71f281..6013975 100755
--- a/samples/pktgen/pktgen.conf-1-1-rdos
+++ b/samples/pktgen/pktgen.conf-1-1-rdos
@@ -18,7 +18,7 @@
 
 
 # thread config
-# Each CPU has own thread. Two CPU exammple. We add eth1, eth2 respectivly.
+# Each CPU has its own thread. One CPU example. We add eth1.
 
 PGDEV=/proc/net/pktgen/kpktgend_0
   echo "Removing all devices"