[ATM]: [he] don't hold the device lock when upcalling

This can create a deadlock/lock ordering problem with other layers
that want to use the transmit (or other) path of the card at that
time.

Signed-off-by: Chas Williams <chas@cmf.nrl.navy.mil>
Signed-off-by: David S. Miller <davem@davemloft.net>