hv_netvsc: remove excessive logging on MTU change

When we change MTU or the number of channels on a netvsc device we get the
following logged:

 hv_netvsc bf5edba8...: net device safe to remove
 hv_netvsc: hv_netvsc channel opened successfully
 hv_netvsc bf5edba8...: Send section size: 6144, Section count:2560
 hv_netvsc bf5edba8...: Device MAC 00:15:5d:1e:91:12 link state up

This information is useful as debug at most.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>