xen-netfront: don't nest queue locks in xennet_connect()

xen-netfront: don't nest queue locks in xennet_connect()

The nesting of the per-queue rx_lock and tx_lock in xennet_connect()
is confusing to both humans and lockdep.  The locking is safe because
this is the only place where the locks are nested in this way but
lockdep still warns.

Instead of adding the missing lockdep annotations, refactor the
locking to avoid the confusing nesting.  This is still safe, because
the xenbus connection state changes are all serialized by the xenwatch
thread.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: David S. Miller <davem@davemloft.net>