net: ethernet: altera: TSE: do not use tx queue lock in tx completion handler

net: ethernet: altera: TSE: do not use tx queue lock in tx completion handler

The driver already uses its private lock for synchronization between xmit
and xmit completion handler making the additional use of the xmit_lock
unnecessary.
Furthermore the driver does not set NETIF_F_LLTX resulting in xmit to be
called with the xmit_lock held and then taking the private lock while xmit
completion handler does the reverse, first take the private lock, then the
xmit_lock.
Fix these issues by not taking the xmit_lock in the tx completion handler.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: David S. Miller <davem@davemloft.net>