Fix upperiface check when ifdown is run with -a

Fix upperiface check when ifdown is run with -a

Ticket: CM-3007
Reviewed By: shm + patch was pasted in the bug for review
Testing Done: ran precommit + maliks test + malik ran his test on his
box

When -a is specified ifupdown2 works on all interfaces and since the the
upperiface check is a bit expensive i had a "skip" on that.
And so far all the user commands i have seen only work on the $IFACE and
not its dependents. So, never hit this case.