[FAB-3684] Default $CHANNEL_NAME is not set

Default $CHANNEL_NAME is not set in e2e_cli/generateArtifacts.sh
This patch fixes the script to set "mychannel" as defalut channel.

Change-Id: Id6dbf33723b7f433463fcee9f5bb265a20736dd1
Signed-off-by: Yuki Kondo <[email protected]>

Author: yuki-kon

examples/e2e_cli/generateArtifacts.sh

@@ -2,8 +2,8 @@
 
 #set -e
 
-: ${CHANNEL_NAME:="mychannel"}
 CHANNEL_NAME=$1
+: ${CHANNEL_NAME:="mychannel"}
 echo $CHANNEL_NAME
 
 export FABRIC_ROOT=$PWD/../..