e1000: stop timers at appropriate times

there were some hotplug cases that made timers still run after the driver
had been removed, make sure to stop all the timers and not allow racy
reschedules.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Don Skidmore <donald.c.skidmore@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>