[BNX2X]: fix HW attentions and error handling

Some of the HW attentions, used to indicate an error were not properly
acked.

This will cause the driver to endlessly receive interrupts when such
an error happens.

Had to break the code into smaller chunks because it got too nested.

Signed-off-by: Eliezer Tamir <eliezert@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>