[Coverity CID :195789]Uninitialized variables in /subsys/usb/class/netusb/function_rndis.c

[aasthagr]

Static code scan issues seen in File: /subsys/usb/class/netusb/function_rndis.c
Category: Uninitialized variables
Function: append_bytes
Component: Other
CID: 195789
Please fix or provide comments to square it off in coverity in the link: https://scan9.coverity.com/reports.htm#v32951/p12996