sky2: fix hang on shutdown (and other irq issues)

There are several problems with recent change to how IRQ's are setup.
   * synchronize_irq in sky2_shutdown would hang because there
     was no IRQ setup.
   * when device was set to down, some IRQ bits left enabled so a
     hardware error would produce IRQ with no handler
   * quick link on Optima chip set was enabled without handler
   * suspend/resume would leave IRQ on with no handler if device
     was down

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>