enic: do not call enic_change_mtu in enic_probe

commit cb5c6568867325f9905e80c96531d963bec8e5ea upstream.

In commit ab123fe071c9 ("enic: handle mtu change for vf properly")
ASSERT_RTNL() is added to _enic_change_mtu() to prevent it from being
called without rtnl held. enic_probe() calls enic_change_mtu()
without rtnl held. At this point netdev is not registered yet.
Remove call to enic_change_mtu and assign the mtu to netdev->mtu.

Fixes: ab123fe071c9 ("enic: handle mtu change for vf properly")
Signed-off-by: Govindarajulu Varadarajan <gvaradar@cisco.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>