[PATCH] e1000: prevent statistics from getting garbled during reset

If a PCI bus error/fault triggers a PCI bus reset, attempts to get the
ethernet packet count statistics from the hardware will fail, returning
garbage data upstream.  This patch skips statistics data collection if the
PCI device is not on the bus.

This patch presumes that an earlier patch,
[PATCH] PCI Error Recovery: e1000 network device driver
has already been applied.

Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: John Ronciak <john.ronciak@intel.com>
Cc: Jesse Brandeburg <jesse.brandeburg@intel.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>