r8169: Rx path update

- pci_dma_sync_single_for_cpu is not needed for a single large packet
- remove the function pointer to help gcc optimizing the inline
  pci_dma functions.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Cc: Edward Hsu <edward_hsu@realtek.com.tw>