imx6: pci: revert OF irq mapping back to 3.10 (r649)

Revert OF irq mapping technique for the 3.14 kernel as it requires
newer devicetrees. Instead, revert back to the 3.10 kernel way of
determining legacy irq mappings (r532).

Signed-off-by: Pushpal Sidhu <psidhu@gateworks.com>

see: http://trac.gateworks.com/changeset/649

target/linux/imx6/patches-3.14/207-pci_designware_revert-pcie-map-irq-function.patch

@@ -0,0 +1,24 @@
+Index: linux-3.14.16/drivers/pci/host/pcie-designware.c
+===================================================================
+--- linux-3.14.16.orig/drivers/pci/host/pcie-designware.c	2014-10-23 15:59:17.978240312 -0700
++++ linux-3.14.16/drivers/pci/host/pcie-designware.c	2014-10-23 16:04:32.478231239 -0700
+@@ -744,9 +744,16 @@
+ 	struct pcie_port *pp = sys_to_pcie(dev->bus->sysdata);
+ 	int irq;
+
+-	irq = of_irq_parse_and_map_pci(dev, slot, pin);
+-	if (!irq)
+-		irq = pp->irq;
++	switch (pin) {
++	case 1: irq = pp->irq; break;
++	case 2: irq = pp->irq - 1; break;
++	case 3: irq = pp->irq - 2; break;
++	case 4: irq = pp->irq - 3; break;
++	default: irq = -1; break;
++	}
++
++	dev_info(&dev->dev, "map_irq: %04x:%04x slot%d pin%d irq%d\n",
++		 dev->vendor, dev->device, slot, pin, irq);
+
+ 	return irq;
+ }