ena: Fix leaking ifmedia resources on detach

[osamaabb_amazon.com]

Summary

ifmedia_add() allocates an ifmedia_entry during ena_attach.
Current code doesn't release this memory during ena_detach()

This commit calls ifmedia_removeall() to properly free the
allocated memory during ena_detach().

This bug was first described in:
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=278100

Approved by: cperciva
MFC after: 2 weeks
Sponsored by: Amazon, Inc.

[zlei]

Do not forget ifmedia_removeall() for the label err_detach.

sys/dev/ena/ena.c

3981

Do not forget this.

[cperciva]

sys/dev/ena/ena.c

3981

@osamaabb_amazon.com You're going to add the ifmedia_removeall call here?

[osamaabb_amazon.com]

sys/dev/ena/ena.c

3981

Nice catch, thanks!

3981

Addressed