qed: Correct slowpath interrupt scheme

When using INTa, ISR might be called before device is configured
for INTa [E.g., due to other device asserting the shared interrupt line],
in which case the ISR would read the SISR registers that shouldn't be
read unless HW is already configured for INTa. This might break interrupts
later on. There's also an MSI-X issue due to this difference, although
it's mostly theoretical.

This patch changes the initialization order, calling request_irq() for the
slowpath interrupt only after the chip is configured for working
in the preferred interrupt mode.

Signed-off-by: Sudarsana Kalluru <Sudarsana.Kalluru@qlogic.com>
Signed-off-by: Manish Chopra <manish.chopra@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>