staging: rts5208: Use pci_device_id rather than DEFINE_PCI_DEVICE_TABLE

This patch enhances kernel style usage for the rts5208 driver.
We should prefer `struct pci_device_id` over `DEFINE_PCI_DEVICE_TABLE` to meet
kernel coding style guidelines. This issue was reported by checkpatch.

Signed-off-by: Benoit Taine <benoit.taine@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>