modify sales order plant code which already created DN

Step1：use t-code VA03（display sales order）to check DN for sales order by "display document flow"

Step2： use t-code：VL02N（change outbound delivery）to delete customer DN

Step3：use t-code：VA02（change sales order ） to correct plant code from USFS to USBW
Step4：use t-code：VL01N（Create outbound delivery） to create customer DN
Step5：confirm delivery in TMS to do PGI for customer DN