qlge: Add watchdog timer.

Add periodic heartbeat register read to trigger the eeh
recovery process.
We see cases where an eeh error was injected and the slot was
suspended.  An asic access attempt is required to flush the recovery process,
but without interrupts the process can stall.
Adding this periodic register read causes the recovery process to begin.

Signed-off-by: Ron Mercer <ron.mercer@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>