Description: Fix double fget() in vhost_net_set_backend()
References:
 https://bugzilla.redhat.com/show_bug.cgi?id=2087568
 https://lore.kernel.org/netdev/20220516084213.26854-1-jasowang@redhat.com/T/
Notes:
Bugs:
upstream: released (5.18) [fb4554c2232e44d595920f4d5c66cf8f7d13f9bc]
6.1-upstream-stable: N/A "Fixed before branching point"
5.10-upstream-stable: released (5.10.118) [ec0d801d1a44d9259377142c6218885ecd685e41]
4.19-upstream-stable: released (4.19.245) [6ca70982c646cc32e458150ee7f2530a24369b8c]
sid: released (5.17.11-1)
5.10-bullseye-security: released (5.10.120-1)
4.19-buster-security: released (4.19.249-1)