via-rhine: Fix bugs in NAPI support.
1) rhine_tx() should use dev_kfree_skb() not dev_kfree_skb_irq()
2) rhine_slow_event_task's NAPI triggering logic is racey, it
should just hit the interrupt mask register. This is the
same as commit
7dbb491878a2c51d372a8890fa45a8ff80358af1
("r8169: avoid NAPI scheduling delay.") made to fix the same
problem in the r8169 driver. From Francois Romieu.
Reported-by: Jamie Gloudon <jamie.gloudon@gmail.com>
Tested-by: Jamie Gloudon <jamie.gloudon@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>