PCI: use fixed-up device class when configuring device

The device class may be changed after the fixup, so re-read the class
value from pci_dev when configuring the device.  Otherwise some devices
such as JMicron SATA controller won't work.

Reviewed-by: Matthew Wilcox <willy@linux.intel.com>
Reviewed-by: Grant Grundler <grundler@parisc-linux.org>
Tested-by: Marc Dionne <marc.c.dionne@gmail.com>
Signed-off-by: Yu Zhao <yu.zhao@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>