Merge branch 'xen-netback-fix-issue-introduced-recently'

Juergen Gross says:

====================
xen/netback: fix issue introduced recently

The fix for XSA-423 introduced a bug which resulted in loss of network
connection in some configurations.

The first patch is fixing the issue, while the second one is removing
a test which isn't needed.
====================

Link: https://lore.kernel.org/r/20230327083646.18690-1-jgross@suse.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>