mpc83xx: MPC837xEMDS: Use hwconfig instead of pci_external_arbiter variable

Since we have simple hwconfig interface now, we don't need
pci_external_arbiter variable any longer.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: Kim Phillips <kim.phillips@freescale.com>

board/freescale/mpc837xemds/mpc837xemds.c

@@ -292,10 +292,9 @@ int board_pci_host_broken(void)
 {
 	struct immap __iomem *im = (struct immap __iomem *)CONFIG_SYS_IMMR;
 	const u32 rcw_mask = HRCWH_PCI1_ARBITER_ENABLE | HRCWH_PCI_HOST;
-	const char *pci_ea = getenv("pci_external_arbiter");
 
 	/* It's always OK in case of external arbiter. */
-	if (pci_ea && !strcmp(pci_ea, "yes"))
+	if (hwconfig_subarg_cmp("pci", "arbiter", "external"))
 		return 0;
 
 	if ((in_be32(&im->reset.rcwh) & rcw_mask) != rcw_mask)