selftests: netdevsim: sprinkle more udevadm settle

Number of tests are failing when netdev renaming is active
on the system. Add udevadm settle in logic determining
the names.

Fixes: 242aaf03dc9b ("selftests: add a test for ethtool pause stats")
Signed-off-by: Jakub Kicinski <[e-mail]>
Reviewed-by: Simon Horman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Paolo Abeni <[e-mail]>

tools/testing/selftests/drivers/net/netdevsim/ethtool-common.sh

···
     fi
 
     echo $NSIM_ID $@ > /sys/bus/netdevsim/new_device
+    udevadm settle
     # get new device name
     ls /sys/bus/netdevsim/devices/netdevsim${NSIM_ID}/net/
 }

tools/testing/selftests/drivers/net/netdevsim/udp_tunnel_nic.sh

···
 function get_netdev_name {
     local -n old=$1
 
+    udevadm settle
     new=$(ls /sys/class/net)
 
     for netdev in $new; do