PCI: Fix unaligned accesses in VC code

The save/restore buffers for VC state is first composed of a 2-byte control
register, then a bunch of 4-byte words.

This causes unaligned accesses which trap on platform such as sparc.

This is easy to fix by simply moving the buffer pointer forward by 4 bytes
instead of 2 after dealing with the control register.  The length
adjustment needs to be changed likewise as well.

Fixes: 5f8fc432 ("PCI: Include pci/pcie/Kconfig directly from pci/Kconfig")
Reported-by: NMeelis Roos <mroos@linux.ee>
Reported-by: NAnatoly Pugachev <matorola@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org	# v4.6+

drivers/pci/vc.c

@@ -221,9 +221,9 @@ static int pci_vc_do_save_buffer(struct pci_dev *dev, int pos,
 		else
 			pci_write_config_word(dev, pos + PCI_VC_PORT_CTRL,
 					      *(u16 *)buf);
-		buf += 2;
+		buf += 4;
 	}
-	len += 2;
+	len += 4;
 
 	/*
 	 * If we have any Low Priority VCs and a VC Arbitration Table Offset