wl1271: handle HW watchdog interrupt

unmask the WL1271_ACX_INTR_WATCHDOG interrupt.
when getting it - enqueue a recovery work and bail out.

Signed-off-by: Eliad Peller <eliad@wizery.com>
Reviewed-by: Luciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: Luciano Coelho <luciano.coelho@nokia.com>