PCI: Remove unused pci_dma_burst_advice()

pci_dma_burst_advice() was added by e24c2d963a ("[PATCH] PCI: DMA
bursting advice") but apparently never used.  Remove it.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Michal Simek <monstr@monstr.eu>	# microblaze
CC: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/sun/cassini.c

@@ -3058,7 +3058,6 @@ static void cas_init_mac(struct cas *cp)
 	/* setup core arbitration weight register */
 	writel(CAWR_RR_DIS, cp->regs + REG_CAWR);
 
-	/* XXX Use pci_dma_burst_advice() */
 #if !defined(CONFIG_SPARC64) && !defined(CONFIG_ALPHA)
 	/* set the infinite burst register for chips that don't have
 	 * pci issues.