ifconfig: Fix configuring if_bridge with additional operating parameters

For clone create and rename operations, the interface name get back can be
different from the one passed to ioctl(). Use the interface name we get back
so that ifconfig will not return unexpected ENXIO.

PR: 270618
Reviewed by: kp
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D39396